Skin Ulcers

Ulcers of the Skin – An Overview

  • Erosions are shallow defects in the skin, which only affect the skin’s upper layers; erosions can be quite painful, but tend to heal quickly if protected (and the underlying cause is eliminated)
  • Ulcers are deeper defects in the skin, where the surface layers are compromised completely; ulcers require careful wound care to prevent infection, and tend to heal slowly
  • Erosive or ulcerative dermatoses are a group of dissimilar skin disorders, characterized by the presence of erosions or ulcers

Genetics

  • Some diseases characterized by erosions or ulcers of the skin are likely inherited since they tend to occur in certain breeds; however, no genetic screening tests are available

Signalment/Description of Pet

Species

  • Dogs
  • Cats

Signs/Observed Changes in the Pet

  • Depend on cause
  • Erosions or ulcers; they may be found anywhere on the body
  • Hair loss (known as “alopecia”)
  • Single or multiple lesions; lesions may be inflamed (indicated by redness)
  • May see lesions over pressure points (such as skin over bones)
  • May have dried discharge on the surface of a skin lesion (known as a “crust”) or may have moist discharge
  • May have loss of pigment of skin and/or hair (known as “depigmentation”)

Causes

  • Wide variety of diseases may result in erosions or ulcers of the skin; common causes are burns, trauma, and skin infections; more complicated diseases, such as drug reactions, certain types of cancers, auto-immune diseases of the skin, and viruses also may cause erosions or ulcers that appear identical to burns or trauma—your pet’s veterinarian may need to run a battery of tests (including bloodwork, cultures for different types of infections, and skin biopsies) to identify the cause and prescribe proper treatment
  • In some cases, an underlying cause cannot be identified and the cause is “unknown,” so-called “idiopathic” disorder or disease
  • Disorders that cause erosions or ulcers of the skin include the following (a partial list):
  • Immune-Mediated Disorders
  • Inflammation of blood vessels (known as “vasculitis”)
  • Canine juvenile cellulitis (puppy strangles)
  • Toxic epidermal necrolysis (usually medication-induced)
  • Feline indolent ulcer (rodent ulcer)
  • Auto-immune disorders (such as pemphigus or lupus) in which the immune system attacks the skin
  • Infectious Disorders
  • Skin infection characterized by the presence of pus (known as “pyoderma”) caused by Staphylococcus
  • Deep fungal or mycotic infections (such as sporotrichosis, cryptococcosis, histoplasmosis)
  • Superficial fungal infections (Malassezia dermatitis, dermatophytosis)
  • Actinomycetic bacteria (such as Nocardia, Actinomyces, Streptomyces)
  • Feline cow pox
  • Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) related disease
  • Parasitic Disorders
  • Demodectic mange (demodicosis)
  • Sarcoptic or notoedric mange
  • Flea-bite allergy
  • Congenital/Hereditary Disorders
  • Various skin disorders in which the skin is abnormal at birth (that is, a “congenital” abnormality) that may or may not be inherited
  • Metabolic Disorders
  • Liver disease
  • Excessive production of steroids by the adrenal glands (known as “hyperadrenocorticism” or “Cushing’s syndrome”), especially when complicated by secondary infections or calcium deposits in the skin (known as “calcinosis cutis”
  • Cancer
  • Squamous cell carcinoma
  • Mast cell tumors
  • Lymphoma of the skin (“mycosis fungoides”)
  • Nutritional Disorder
  • Zinc-responsive dermatosis
  • Generic dog-food dermatosis
  • Miscellaneous
  • Thermal, electrical, solar, or chemical burns
  • Frost bite
  • Chemical irritants
  • Venomous snake and insect bites

Risk Factors

  • Depend on underlying cause

Treatment

Health Care

  • Outpatient for most diseases
  • Varies widely according to the cause
  • Keeping eroded or ulcerated skin clean and protected are key to healing; if the cause is known, specific drug therapies may be prescribed
  • Pain management may be necessary for some pets, based on cause of condition
  • Your veterinarian will tailor a management program that is best for your pet’s individual case
  • Hydrotherapy, which may be achieved with either a whirlpool bath or by spraying cool water under pressure against the ulcerated skin can be helpful in many cases; ask your pet’s veterinarian first to be sure that hydrotherapy is appropriate for your pet’s condition
  • Avoid the temptation to apply “over-the-counter” creams and ointments to erosions and ulcers, without first checking with your veterinarian—some commonly used products (such as those containing neomycin) actually may delay healing in some cases; other products may contain types of alcohol or other ingredients that could cause pain upon application

Diet

  • Supportive therapy with fluid and nutritional supplementation is indicated in cases with severe fluid and protein loss through the damaged skin
  • Good quality diet
  • Supplementation of zinc in the diet for pets with zinc-responsive skin conditions

Surgery

  • Skin biopsy may be necessary for diagnosis

Medications

Vary widely according to cause.

Follow-Up Care

Patient Monitoring

  • Case-by-case basis, depending on the disease process, presence of generalized (systemic) disease(s), medications used, and potential side effects expected
  • Follow-up care is important, especially for slowly healing ulcers; a veterinarian should check progress of the wound at least every other week to be sure that healing is proceeding properly and that infection has not complicated the healing process

Possible Complications

  • Depend on cause
  • Some diseases are potentially life-threatening
  • Some diseases are caused by agents that may be spread to people (known as having “zoonotic potential”)
  • Superinfections and drug side effects are possible in cases requiring medications to decrease the body’s immune response (known as “immunosuppression”)
  • Some infectious diseases (such as nocardiosis, atypical mycobacteriosis) may be controlled, but not cured

Expected Course and Prognosis

  • Vary widely according to cause

Key Points

  • Wide variety of diseases may result in erosions or ulcers of the skin; common causes are burns, trauma, and skin infections; more complicated diseases, such as drug reactions, certain types of cancers, auto-immune diseases of the skin, and viruses also may cause erosions or ulcers that appear identical to burns or trauma—your pet’s veterinarian may need to run a battery of tests (including bloodwork, cultures for different types of infections, and skin biopsies) to identify the cause and prescribe proper treatment
  • Follow-up care is important, especially for slowly healing ulcers; a veterinarian should check progress of the wound at least every other week to be sure that healing is proceeding properly and that infection has not complicated the healing process

Skin Inflammation

Inflammation of the Skin and Muscles (Dermatomyositis) – An Overview

  • “Dermatomyositis” is an inherited inflammatory disease of the skin, muscles, and blood vessels that develops in young collies, Shetland sheepdogs, and their crossbreeds

Genetics

  • Collies and Shetland sheepdogs—inherited as an autosomal dominant trait, with variable expression

Signalment/Description of Pet

Species

  • Dogs

Breed Predilections

  • Collies, Shetland sheepdogs, and their crossbreeds
  • Similar signs have been reported in other breeds, such as the Beauceron shepherd, Welsh corgi, Lakeland terrier, chow chow, German shepherd dog, and Kuvasz
  • Some dogs in other breeds with similar signs are now classified as having “ischemic dermatopathy” (dermatomyositis-like skin disease) and not “dermatomyositis” as previously reported

Mean Age and Range

  • Skin lesions typically develop before six months of age, and may develop as early as 7 weeks of age
  • The full extent of lesions usually is present by 1 year of age, and may lessen thereafter
  • Adult-onset dermatomyositis can occur, but is rare

Signs/Observed Changes in the Pet

  • Clinical signs vary from subtle skin lesions and inflammation of muscles that is does not cause clinical signs (known as “subclinical myositis”) to severe skin lesions and a generalized decrease in muscle mass (known as “muscle atrophy”) with an abnormal gait, and an enlarged esophagus (part of the digestive tract, the tube running from the throat to the stomach; condition known as “megaesophagus”)
  • Skin lesions around the eyes, lips, face, inner surface of the prick ears, tip of the tail, and bony prominences vary in intensity; the entire face may be involved—skin lesions may increase and decrease over time (known as a “waxing and waning” course); signs usually seen in affected dogs before they are 6 months of age
  • Skin lesions—characterized by variable degrees of crusted areas with loss of the top surface of the skin (known as “erosions” or “ ulcers” based on depth of tissue loss) and hair loss (known as “alopecia”), with reddening of the skin (known as “erythema”), accumulations of surface skin cells, such as seen in dandruff (known as “scales”), and scars
  • Pressure points and exposed areas of skin over boney prominences commonly are affected first
  • Scars may occur as a sequela to initial skin lesions
  • More severely affected dogs may have difficulty eating, drinking, and swallowing
  • Stiff or high-stepping gait
  • Several litter mates may be affected, but the severity of the disease often varies significantly among affected dogs
  • Foot-pad ulcers and ulcers in the mouth, as well as nail abnormalities or loss, may occur
  • Inflammation of the muscles (myositis)—signs may be absent or vary from subtle decrease in the mass of the muscles extending from the top and side of the head, behind the eye, to the lower jaw (known as the “temporal muscles”) to generalized, symmetric loss of muscle mass (muscle atrophy) and stiff or high-stepping gait
  • Decrease in muscle mass (muscle atrophy) of the muscles extending from the bone below the eye to the lower jaw (known as the “masseter muscles”) that act to close the jaw and muscles extending from the top and side of the head, behind the eye, to the lower jaw (temporal muscles) that act to close the jaw—may be evident
  • Dogs with enlarged esophagus (megaesophagus) may present with aspiration pneumonia (inflammation of the lungs, caused by accidentally inhaling food, vomit, or liquids)

Causes

  • Hereditary in the collie, Shetland sheepdog, and their crosses
  • Infectious agents or medications may be triggering events
  • Immune-mediated disease in other dog breeds

Risk Factors

  • Mechanical pressure and trauma, and ultraviolet-light exposure may worsen skin lesions

Treatment

Health Care

  • Most dogs can be treated as outpatients
  • Dogs with severe inflammation of the muscles (myositis) and enlarged esophagus (megaesophagus) may need to be hospitalized for supportive care
  • Euthanasia may be indicated in severe cases

Activity

  • Avoid activities that may traumatize the skin
  • Keep indoors during the day to avoid exposure to intense sunlight

Diet

  • May need to change diet, if dog has enlarged esophagus (megaesophagus) or has difficulty eating and/or swallowing
  • Feed dog with food bowl elevated if enlarged esophagus (megaesophagus) develops
  • Assist dog with eating, if muscles involved with chewing are affected

Surgery

  • Skin biopsy—may be diagnostic for dermatomyositis, although this disease can be difficult to diagnose definitively
  • Muscle biopsy

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive:

  • Non-specific symptomatic therapy includes hypoallergenic shampoo baths, treating secondary bacterial skin infections and Demodex mange (known as “demodicosis”), and avoiding trauma and sunlight
  • Vitamin E
  • Essential fatty acid supplements
  • Steroids (such as prednisone) to decrease inflammation
  • Nonsteroidal anti-inflammatory drugs (NSAIDs), as prescribed by your pet’s veterinarian
  • Pentoxifylline to improve blood flow and to reduce inflammation

Follow-Up Care

Preventions and Avoidance

  • Do not breed affected pets
  • Neuter intact pets to decrease the influence of hormones on clinical signs
  • Minimize trauma and exposure to sunlight

Possible Complicatoins

  • Secondary bacterial skin infection and Demodex mange (demodicosis)
  • Mildly to moderately affected dogs may have residual scarring
  • Severely affected dogs may have trouble chewing, drinking, and swallowing
  • Enlarged esophagus (megaesophagus) may develop, increasing the likelihood of aspiration pneumonia

Expected Course and Prognosis

  • The effectiveness of medical treatment can be difficult to assess because the disease tends to be cyclic in nature and often is self-limiting
  • Long-term prognosis—variable, depending on severity of disease
  • Minimal disease—prognosis good; tends to resolve spontaneously with no evidence of scarring
  • Mild to moderate disease—tends to resolve spontaneously, but residual scarring is common
  • Severe disease—prognosis for long-term survival is poor as the inflammation of the skin (known as “dermatitis”) and muscles (myositis) may be lifelong

Key Points

  • Dermatomyositis is considered an inherited disease in collies, Shetland sheepdogs, and their respective crosses
  • Affected dogs should not be used for breeding
  • The disease is not curable, although spontaneous resolution or waxing and waning of signs may occur

Pigment Loss

Loss of Pigment in Dogs & Cats

Overview

  • Disease or cosmetic condition involving loss of pigmentation of the skin and/or hair coat either by lack of pigmentation or by melanocyte damage; “melanocytes” are cells that produce pigment in the skin or hair
  • Normal pigment in the skin and hair coat is melanin
  • “Leukotrichia” is the medical term of whitening of the hair, without indication of location of the whitened hairs
  • “Poliosis” is the medical term of whitening of the hair on the head and/or face
  • “Leukoderma” is the medical term of whitening of the skin

Signalment/Description of Pet

Species

  • Dogs
  • Cats

Breed Predilections

  • Mucocutaneous pyoderma (bacterial skin infection involving areas of the lips, eyelids, nostrils)—German shepherd dogs
  • Systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs) and discoid lupus erythematosus (auto-immune disease involving the skin only, usually the face)—collies, Shetland sheepdogs, German shepherd dogs
  • Pemphigus foliaceous (auto-immune disease involving the skin, characterized by inflammation with crusting and lesions containing pus)—chow chows, Akitas
  • Uveodermatologic syndrome (a rare syndrome in which the pet has inflammation in the front part of the eye, including the iris [condition known as “anterior uveitis”] and coexistent inflammation of the skin [known as “dermatitis”], characterized by loss of pigment in the skin of the nose and lips)—Akitas, Samoyeds, Siberian huskies
  • Vitiligo (condition characterized by symmetrical lack of pigment in the skin and white hair coat, especially involving the face and nose) in dogs—Belgian Tervuren, German shepherd dogs, Doberman pinschers, rottweilers, German shorthaired pointer, Old English sheepdog, and dachshund
  • Seasonal nasal hypopigmentation (loss of pigment in the tough, hairless skin of the nose [known as the “nasal planum”] that occurs seasonally)—Siberian huskies, Alaskan malamutes, yellow Labrador retrievers, and golden retrievers
  • Proliferative arteritis of the nasal philtrum (inflammation of the arteries of the nasal philtrum, the juncture between the sides of the upper lip extending to the nose)—Saint Bernards, giant schnauzers
  • Vitiligo in cats–Siamese
  • Periocular leukotrichia (whitening of the hair coat around the eyes) in cats–Siamese
  • Chediak-Higashi syndrome (an inherited disorder that affects many tissues in the body; causes lack of pigment in the skin and eyes)–Persian

Mean Age and Range

  • Vitiligo (condition characterized by symmetrical lack of pigment in the skin and white hair coat, especially involving the face and nose) in dogs—usually less than 3 years of age
  • Epitholiotropic lymphoma (a type of skin cancer; also known as “mycosis fungoides”)—typically dogs over 10 years of age

Predominant Sex

  • Discoid lupus erythematosus (auto-immune disease involving the skin only, usually the face)—may occur more often in females than in males
  • Vitiligo in Siamese cats—females

Signs/Observed Changes in the Pet

  • White hair (known as “leukotrichia”)
  • Partial or total lack of pigment in the skin (known as “leukoderma”)
  • Lightening of the pigment in the skin, often seen as a “graying” or “browning” of previously pigmented areas
  • Reddening of the skin (known as “erythema”)
  • Loss of the top surface of the skin (known as “erosion” or “ulceration,” based on depth of tissue loss)

Causes

  • Mucocutaneous pyoderma (bacterial skin infection involving areas of the lips, eyelids, nostrils)
  • Systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs)
  • Discoid lupus erythematosus (auto-immune disease involving the skin only, usually the face)
  • Pemphigus foliaceous (auto-immune disease involving the skin, characterized by inflammation with crusting and lesions containing pus)
  • Pemphigus erythematosus (auto-immune disease involving the skin of the face and ears, characterized by reddening of the skin [erythema] and lesions containing pus)
  • Uveodermatologic syndrome (a rare syndrome in which the pet has inflammation in the front part of the eye, including the iris [anterior uveitis] and coexistent inflammation of the skin [dermatitis], characterized by loss of pigment in the skin of the nose and lips)
  • Contact hypersensitivity (increased sensitivity or reaction in the skin to the presence of a foreign agent that comes in contact with the skin)
  • Vitiligo (condition characterized by symmetrical lack of pigment in the skin and white hair coat, especially involving the face and nose)
  • Seasonal nasal depigmentation (loss of pigment in the tough, hairless skin of the nose [known as the “nasal planum”] that occurs seasonally)
  • Albinism (inherited disorders characterized by lack of pigment in the skin, hair, and/or eyes, due to abnormal production of melanin)
  • Schnauzer gliding syndrom (young, gray miniature schnauzers develop golden hair color, primarily in the body)
  • Hormonal disorders
  • Drug reaction
  • Erythema multiforme (skin disorder caused by reaction of medications, infections, or other diseases)
  • Proliferative arteritis of the nasal philtrum (inflammation of the arteries of the nasal philtrum, the juncture between the sides of the upper lip extending to the nose)
  • Loss of pigment in the skin and/or hair following skin inflammation
  • Dermatophytosis (fungal infection on the surface of the skin)

Risk Factors

  • Sun exposure—systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs), discoid lupus erythematosus (auto-immune disease involving the skin only, usually the face), and pemphigus erythematosus (auto-immune disease involving the skin of the face and ears, characterized by reddening of the skin [erythema] and lesions containing pus)

Treatment

Health Care

  • Outpatient, except for systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs), erythema multiforme (skin disorder caused by reaction to medications, infections, or other diseases), and lymphoma of the skin (a type of skin cancer), when severe multiple organ dysfunction is present
  • Reduce exposure to sunlight—systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs), discoid lupus erythematosus (auto-immune disease involving the skin only, usually the face) and pemphigus erythematosus (auto-immune disease involving the skin of the face and ears, characterized by reddening of the skin [erythema] and lesions containing pus)
  • Replace plastic or rubber dishes—particularly if roughened edges cause abrasions
  • Application of water-resistant sun-block ointments or gels (with a SPF UVA and UVB greater than 30) to depigmented areas
  • Vitiligo and nasal depigmentation–no treatment

Activity

  • Restrict outdoor activity to minimize exposure to sunlight—systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs), discoid lupus erythematosus (auto-immune disease involving the skin only, usually the face) and pemphigus erythematosus (auto-immune disease involving the skin of the face and ears, characterized by reddening of the skin [erythema] and lesions containing pus)

Surgery

  • Skin biopsy

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

  • Vary based on underlying cause
  • Systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs)—immunosuppressive therapy with steroids (such as prednisolone or dexamethasone) and chemotherapy drugs (such as azathioprine [dogs] or chlorambucil [cats])
  • Tetracycline and niacinamide—to treat pemphigus erythematosis (auto-immune disease involving the skin of the face and ears, characterized by reddening of the skin [erythema] and lesions containing pus) and discoid lupus erythematosus (auto-immune disease involving the skin only, usually the face) in dogs
  • Medications to decrease the immune response (known as “immunosuppressive therapy”)—to treat systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs), pemphigus foliaceous (auto-immune disease involving the skin, characterized by inflammation with crusting and lesions containing pus), pemphigus erythematosus (auto-immune disease involving the skin of the face and ears, characterized by reddening of the skin [erythema] and lesions containing pus)
  • Cyclosporine to decrease the immune response in auto-immune disorders
  • Steroids applied to the skin directly (known as “topical steroids”)
  • Tacrolimus, 0.1% gel or pimecrolimus 1% cream applied daily to lesions in combination with or to replace steroids
  • Imiquimod 5% cream for actinic keratosis (a precancerous skin condition caused by sun exposure)
  • Antibiotics–trimethoprim-sulfadiazine, cephalexin, or amoxicillin-clavulanate; effective in some cats
  • Antibiotics for bacterial skin infection (known as “pyoderma”)
  • Chlorambucil, a chemoterapeutic drug
  • Medications to treat fungal infections (known as “antifungal drugs”) to treat dermatophytosis (fungal infection on the surface of the skin)

Follow-Up Care

Patient Monitoring

  • Varies with specific disease and treatment prescribed

Preventions and Avoidance

  • Restrict outdoor activity to minimize exposure to sunlight—systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs), discoid lupus erythematosus (auto-immune disease involving the skin only, usually the face) and pemphigus erythematosus (auto-immune disease involving the skin of the face and ears, characterized by reddening of the skin [erythema] and lesions containing pus)

Possible Complications

  • Systemic lupus erythematosus (auto-immune disease in which the body attacks its own skin and other organs)—scarring
  • Squamous cell carcinoma ( a type of skin cancer) in cases of sun-damage to the skin, with resulting loss of skin pigment

Expected Course and Prognosis

  • Vary with specific disease

Mange (Demodectic)

Mange (Demodectic) – An Overview

  • An inflammatory parasitic skin disease of dogs and rarely cats, caused by a species of the mite genus, Demodex
  • Skin disease is characterized by an increased number of mites in the hair follicles and top layer of the skin (known as the “epidermis”), which often leads to secondary bacterial infections and infections deep in the hair follicles, often with resultant rupturing of the hair follicle (known as “furunculosis”)
  • May be localized (in which one or a few small patches of affected skin are present, frequently seen on the face or forelegs) or generalized (in which numerous skin lesions are present on the head, legs, and body)
  • “Demodectic mange,” “demodicosis,” and “red mange” (dogs) are all terms for the same skin disease
  • Three species of Demodex mites have been identified in dogs: Demodex canis, Demodex injai, and Demodex cornei; two species have been identified in cats:Demodex cati and Demodex gatoi

Genetics

  • The initial increase in number of demodectic mites in the hair follicles may be the result of a genetic disorder

Signalment/Description of Pet

Species

  • Dogs – common
  • Cats – rare

Breed Predilections

  • West Highland white terrier and wirehaired fox terrier—greasy inflammation of the skin with increased accumulations of surface skin cells, such as seen in dandruff (accumulations known as “scales”; condition known as “seborrheic dermatitis”) associated with Demodex injai
  • Potential of demodectic mange in cats is increased in Siamese and Burmese

Mean Age and Range

  • Localized demodectic mange (in which one or a few small patches of affected skin are present, frequently seen on the face or forelegs)—usually in young dogs; median age is 3–6 months
  • Generalized demodectic mange (in which numerous skin lesions are present on the head, legs, and body)—both young and old dogs
  • No age data collected for the cat

Signs/Observed Changes in the Pet

Dogs

Localized, Juvenile-Onset
  • One or a few small patches of affected skin are present, frequently seen on the face or forelegs
  • Lesions—usually mild; consist of reddened skin (known as “erythema”) and a light accumulations of surface skin cells, such as seen in dandruff (scales)
  • Patches—several may be noted; most common site is the face, especially around the mouth and eyes and on the front legs; also may be seen on the trunk and rear legs
Generalized, Juvenile-Onset or Adult-Onset
  • Numerous skin lesions are present on the head, legs, and body
  • Can be widespread from the onset, with multiple, poorly circumscribed patches of reddened skin (erythema), hair loss (known as “alopecia”), and accumulations of surface skin cells, such as seen in dandruff (scales)
  • As hair follicles become distended with large numbers of mites, secondary bacterial infections , often with resultant rupturing of the hair follicle (furunculosis) are common
  • With progression of disease, the skin can become severely inflamed, leading to the escape of fluid and inflammatory cells in or on the skin (known as “exudation”), and the development of nodular, inflammatory lesions (known as “granulomas”)
  • Demodex injai may be associated with a greasy inflammation of the skin with increased accumulations of surface skin cells, such as seen in dandruff (accumulations are “scales”; condition is “seborrheic dermatitis”) of the dorsal trunk, plugs of keratin and oil in the follicles of the skin (known as “comedones”), reddened skin (erythema), hair loss (alopecia), and darkening of the skin (known as “hyperpigmentation”)

Cats

  • Often characterized by multiple partial to complete areas of hair loss (alopecia) of the eyelids, as well as the skin around the eyes, head, neck, flank and the under surface of the body
  • Lesions—variable itchiness (known as “pruritus”) with reddened skin (erythema), accumulations of surface skin cells, such as seen in dandruff (scales), and dried discharge on the surface of the skin lesions (known as “crusts”); those caused by Demodex gatoi often are quite itchy (pruritic) and may be contagious
  • Inflammation of the outer ear, characterized by the presence of waxy material (known as “ceruminous otitis externa”) has been reported
  • Demodex cati often is associated with a disease that decreases the immune response (known as “immunosuppressive disease”)

Causes

  • Dog—Demodex canis, Demodex injai, and Demodex cornei
  • Cat—Demodex cati and Demodex gatoi

Risk Factors

Dogs

  • Exact mechanism related to the influence of the immune system on demodectic mange is unknown
  • Studies indicate that dogs with generalized demodectic mange (in which numerous skin lesions are present on the head, legs, and body) have a subnormal percentage of interleukin-2 (IL-2) receptors on their lymphocytes and subnormal IL-2 production; “lymphocytes” are a type of white-blood cell that are formed in lymphatic tissues throughout the body; lymphocytes are involved in the immune process
  • Genetic factors (especially for localized, juvenile-onset demodectic mange), decreased ability to produce a normal immune response (immunosuppression), and/or metabolic diseases may increase the likelihood that the dog will develop demodectic mange

Cats

  • Often associated with metabolic diseases (such as feline immunodeficiency virus [FIV], systemic lupus erythematosus [autoimmune disease in which body attacks its own skin and other organs], diabetes mellitus [sugar diabetes])
  • Demodex gatoi—may be transferable from cat to cat within the same household

Treatment

Health Care

  • Outpatient
  • Localized demodectic mange (in which one or a few small patches of affected skin are present, frequently seen on the face or forelegs)—conservative; most cases (90%) resolve spontaneously with no treatment
  • Generalized demodectic mange (in which numerous skin lesions are present on the head, legs, and body) in dogs—requires application of medication to kill the mites directly onto the skin (known as “topical treatment”) and/or medications administered by mouth (known as “systemic treatment”); antibiotics may be necessary to treat secondary bacterial skin infections
  • Evaluate the general health status of dogs with either localized or generalized demodectic mange

Medications

  • Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive

Amitraz (Mitaban; Taktic EC; ProMeris)

  • A treatment that is applied directly to the skin (topical treatment) to kill demodectic mange mites; agents that kill mites are known as “miticides”
  • Use weekly to every-other-week until resolution of clinical signs and no mites are found on skin scrapings; do not rinse off; let air-dry; use as directed by your pet’s veterinarian
  • ProMeris—apply to skin every 2–4 weeks
  • Treat for 1 month following negative skin scrape
  • Apply a benzoyl peroxide shampoo before application of the amitraz to kill bacteria (known as “bactericidal therapy”) and to increase exposure of the mites to the miticide through flushing activity of the hair follicles
  • Between 11% and 30% of cases will not be cured; may need to try an alternative therapy or control with maintenance treatment every 2–8 weeks
  • Rarely used in cats (do not use on diabetic cats)

Ivermectin

  • Dog—daily administration by mouth has been very effective, even when amitraz fails; use as directed by your pet’s veterinarian
  • Treat for 30–60 days beyond negative skin scrapings (average length of treatment is 3–8 months)
  • Reported as a treatment option in the cat; exact dose has not been established

Milbemycin (Interceptor)

  • Administered by mouth
  • Has been effective in 50–85% of cases
  • Treat for 30–60 days beyond multiple negative skin scrapings
  • Very expensive

Cats

  • Exact treatment protocols are not defined
  • Lime-sulfur dips applied to the skin (topical treatment) every 3–7 days for 4–8 treatments is the suggested treatment; often lead to good resolution of clinical signs
  • Studies of treatment with ivermectin and milbemycin are lacking, although numerous anecdotal reports suggest effectiveness
  • Doramectin also has been reported to be effective when given by injection under the skin (subcutaneous route) once weekly

Follow-Up Care

Patient Monitoring

  • Repeat skin scrapings and monitor for evidence of resolution of signs

Preventions and Avoidance

  • Do not breed pets with generalized form of demodectic mange (in which numerous skin lesions are present on the head, legs, and body)

Possible Complications

  • Secondary bacterial infections and infections deep in the hair follicles, often with resultant rupturing of the hair follicle (furunculosis)

Expected Course and Prognosis

  • Prognosis (dogs)—depends heavily on genetics, status of the immune system, and underlying diseases
  • Localized demodectic mange (in which one or a few small patches of affected skin are present, frequently seen on the face or forelegs)—most cases (90%) resolve spontaneously with no treatment; less than 10% of localized demodectic mange cases progress to generalized demodectic mange (in which numerous skin lesions are present on the head, legs, and body)
  • Adult-onset of demodectic mange in dogs—often severe disease and poorly responsive to non-responsive to treatment
  • Feline cases with Demodex cati may have a poor prognosis associated with underlying disease

Key Points

  • Localized demodectic mange (in which one or a few small patches of affected skin are present, frequently seen on the face or forelegs)—most cases resolve spontaneously
  • Generalized demodectic mange (in which numerous skin lesions are present on the head, legs, and body)—frequent management problem; expense and frustration with the long-term (chronic) nature of disease and treatment are issues; many cases are medically controlled, not cured; juvenile-onset is considered to have a genetic influence and affected animals should not be used for breeding

Itchiness in Dogs & Cats

Itchiness in Dogs & Cats – An Overview

  • “Pruritus” is the medical term for itching or itchiness; it is the itching sensation that provokes the desire to scratch, rub, chew or lick
  • Pruritus is an indicator of inflamed skin
  • The term is not a diagnosis but rather is a description of a clinical sign

Species

  • Dogs
  • Cats

Signs/Observed Changes in the Pet

  • Scratching
  • Licking
  • Biting
  • Rubbing
  • Chewing
  • Self-trauma
  • Inflammation of the skin (known as “dermatitis”)
  • Hair loss (known as “alopecia”); hair loss without inflammation may be the only sign in some cats
  • Other signs determined by underlying cause

Causes

  • Parasites—fleas; mites (canine scabies [Sarcoptes], Demodex, ear mites [Otodectes], feline scabies [Notoedres], “walking dandruff” [Cheyletiella], harvest mite or red bud [Trombicula]); lice; rhabditic dermatitis (Pelodera strongyloides); or migration of internal parasites
  • Allergies—parasite allergy; atopy (disease in which the pet is sensitized [or “allergic”] to substances found in the environment [such as pollen] that normally would not cause any health problems); food allergy; contact allergy; drug allergy; allergy to skin bacteria (known as “bacterial hypersensitivity”); allergy to Malassezia (a yeast found on the skin)
  • Bacterial or fungal infections—Staphylococcus (a bacteria) and Malassezia pachydermatis (a yeast or fungus); rarely a dermatophyte (fungus living on the skin, hair, or nails); however, Trichophyton is a dermatophyte that tends to cause more itchy skin disease than the other dermatophytes
  • Miscellaneous—excessive scaling of the skin (known as “seborrhea”); calcium deposits in the skin (known as “calcinosis cutis”); skin tumors or cancer
  • Immune-mediated skin diseases and hormonal skin diseases can be variably itchy
  • Psychological skin diseases may be associated with itchiness

Risk Factors

  • Exposure to other animals with parasites

Treatment

Health Care

  • More than one disease can contribute to itching
  • The use of mechanical restraint (such as an Elizabeth collar) can be a helpful option, but is seldom feasible in long-term treatment
  • Treat for secondary infections, which are common

Diet

  • Depends on underlying cause
  • Usually no change in diet needed, unless suspected food allergey

Medication

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive

Medications Applied to the Skin Directly (Known as “Topical Therapy”)

  • Topical therapy is helpful in mildly itchy pets
  • For localized areas of itchiness or skin inflammation, sprays, lotions and creams are most appropriate
  • If the itching involves many areas or widespread areas, shampoos are the preferred means of application
  • Antibacterial shampoos help control bacterial infections that cause itching; however, some antibacterial shampoos (such as those containing benzoyl peroxide or iodine) can cause increased itching
  • Colloidal oatmeal is common in all forms of topical therapy; its duration of effect usually is less than two days
  • Topical antihistamines may be found alone or in combination with other ingredients; they may not have a beneficial effect
  • Topical anesthetics may offer only a very short duration of effect
  • Antimicrobial shampoos help control bacterial infections that cause itching; however, some contain ingredients (such as benzoyl peroxide or iodine) that can increase itchiness through excessive drying
  • Lime sulfur (which has a bad odor and can stain) can decrease itching, while also having anti-parasitic, antibacterial, and antifungal properties
  • Topical steroids probably are the most useful topical medications; hydrocortisone is the mildest and most common topical steroid; stronger steroids (such as betamethasone) may be more effective and are more expensive; a triamcinolone-containing prescription spray (Genesis® Topical Spray, Virbac) is effective in decreasing itchiness (pruritus)
  • Some topical steroid medications also contain ingredients (such as alcohol), which can aggravate already irritated skin
  • In some pets, the application of any substance, including water (especially warm water), can result in an increased level of itchiness; however, cool water often is soothing

Medications Administered by Mouth or by Injection (Systemic Therapy)

  • Steroids to decrease inflammation and itchiness of the skin
  • Cyclosporine to decrease the immune response
  • For pets affected with airborne allergies for more than a few months out of the year, “allergy shots” (known as “allergen specific immunotherapy”) are appropriate, frequently beneficial, and may lead to a cure (in some cases)
  • Antihistamines (such as hydroxyzine, diphenhydramine, and chlorpheniramine) to prevent inflammation and itching
  • Fatty acids are available in powders, liquids, and capsules; they help block pathways that lead to inflammation, but may require 6–8 weeks of use until maximum effect is observed; fatty acids work better as preventive medications, rather than stopping the inflammation once it has become a problem; they also help reduce dry or flaky skin, which can cause itching
  • Medications to relieve anxiety or depression (known as “psychogenic drugs”) can be helpful in controlling itchiness; include such drugs as amitriptyline, fluoxetine, and diazepam
  • In rare cases, alternative medications to decrease the immune response (known as “immunosuppressive drugs,” such as azathioprine) may be utilized; however, they should be reserved for instances when all other treatments have failed

Follow-Up Care

Patient Monitoring

  • Patient monitoring is imperative; pets should be examined periodically to evaluate response to treatment
  • Pets receiving long-term (chronic) medications should be evaluated every 3–12 months for potential side effects as well as occurrence of new contributing factors

Preventions and Avoidance

  • Prevent infestation with parasites (such as fleas and mites)
  • Avoid foods identified as causing food allergy for your pet

Possible Complications

  • Owner frustration is common
  • Complications (such as increased thirst [known as “polydipsia”] and increased urination [known as “polyuria”]) are common with long-term (chronic) steroid use

Expected Course and Prognosis

  • Depend on underlying cause
  • Many causes of itchiness in pets are extremely frustrating to control

Key Points

  • Many different unrelated diseases may contribute to itchiness (pruritus), and control of one disease does not mean that other causes cannot be contributing to itchiness or cannot occur later
  • Multiple causes (such as flea allergy, inhalant allergy, and bacterial skin infection [known as “pyoderma”]) commonly are present in a single patient
  • Elimination of bacterial skin infection (pyoderma) and flea-associated disease may not be enough to significantly reduce itchiness
  • Food-allergy and inhalant-allergic pets may do well during the winter season with a hypoallergenic diet, only to become itchy during the warmer months in association with inhalant allergies

Hair Loss with No Skin Inflammation

Hair Loss Without Inflammation of The Skin in Dogs — An Overview

  • “Alopecia” is the medical term for hair loss
  • Non-inflammatory alopecia is a group of uncommon skin disorders, characterized by hair loss that is associated with an abnormal hair growth/shed cycle
  • Hormonal and non-hormonal diseases can be associated with non-inflammatory hair loss (alopecia)
  • Alopecia X is a non-inflammatory alopecia related to an abnormal hair growth/shed cycle; it has been called by many names previously, including “growth hormone-responsive alopecia,” “castration-responsive alopecia,” and “adrenal hyperplasia-like syndrome”
  • “Estrogen,” “progesterone,” and “estradiol” are female hormones; “testosterone” and “androgen” are male hormones
  • An “intact” pet is one that has its reproductive organs; an “intact female” has her ovaries and uterus and an “intact male” has his testicles
  • A “neutered” pet has had its reproductive organs surgically removed; females commonly are identified as “spayed,” but may be identified as “neutered”; males may be identified as “castrated” or “neutered”

Genetics

  • Breed predilections exist for alopecia X; however, the mode of inheritance is unknown

Signalment/Description of Pet

Species

  • Dogs

Breed Predilections

  • Increased levels of estrogen (known as “hyperestrogenism”) in females and increased levels of androgen (known as “hyperandrogenism”) in males—none
  • Alopecia X—miniature poodle and plush-coated breeds, such as the Pomeranian, chow chow, Akita, Samoyed, Keeshonden, Alaskan malamute, and Siberian husky

Mean Age and Range

  • Increased levels of estrogen (hyperestrogenism) in females and increased levels of androgen (hyperandrogenism) in males—middle-aged to old, intact dogs
  • Alopecia X—range, 1–5 years of age; older dogs may develop alopecia X

Predominant Sex

  • Increased levels of estrogen (hyperestrogenism)—primarily intact female or male dogs; male dogs due to testicular cancer producing excessive levels of estrogen
  • Increased levels of androgen (hyperandrogenism)—primarily intact males
  • Alopecia X—neutered or intact dogs of either sex

Signs/Observed Changes in The Pet

  • Overall change in the hair coat—dry or bleached, because hairs are not being replaced; lack of normal shedding
  • Male dogs with increased levels of estrogen (hyperestrogenism) may attract other male dogs
  • Hair loss (alopecia)—usually generalized and bilaterally symmetrical; involves the trunk, along the sides of the body (known as “truncal alopecia”) and spares the head and lower legs; hair loss is uncommon in dogs with increased levels of androgens (hyperandrogenism)
  • Secondary excessively oily or dry scaling of the skin (known as “seborrhea”); itchiness (known as “pruritus”); skin infection characterized by the presence of pus (known as “pyoderma”); hair follicles filled with oil and skin cells (known as “comedones”); inflammation of the outer ear, characterized by an oily discharge (known as “ceruminous otitis externa”); and darkened skin (known as “hyperpigmentation”)—variable
  • Enlargement of nipples, mammary glands, vulva (external genitalia of the female), prepuce (fold of skin that covers the penis)—may be associated with increased levels of estrogen (hyperestrogenism)
  • Abnormal sized testicles—may be associated with increased levels of estrogen (hyperestrogenism) or increased levels of androgen (hyperadrogenism); however, testicles may be normal in size
  • Increase in the number of cells in the tail glands (known as “tail gland hyperplasia”) and increase in the number of cells in the perianal gland (known as “perianal gland hyperplasia”) with localized change in color of the skin due to deposits of melanin (known as “macular melanosis”)
  • Signs of generalized disease (known as “systemic signs”), such as increased thirst (known as “polydipsia”), increased urination (known as “polyuria”), or increased appetite (known as “polyphagia”) are NOT present

Causes

Skin Disorders due to Increased Levels of Estrogen (Hyperestrogenism)–Female

  • Estrogen excess or imbalance owing to a condition characterized by the presence of fluid-filled sacs or cysts in the ovaries (cystic ovaries), ovarian tumors (rare), or excess/overdose of estrogen-containing medications
  • Pets with normal serum estrogen concentrations may have a increased number of estrogen receptors in the skin

Skin Disorders due to Increased Levels of Estrogen (Hyperestrogenism)–Male Dogs with Testicular Tumors

  • Estrogen excess due to a tumor in the testicles, such as Sertoli cell tumor (most common), seminoma, or interstitial cell tumor (rarely)
  • Lack of normal descent of one or both testicles into the scrotum, resulting in the testicle(s) being located in the abdomen or inguinal canal (known as “cryptorchidism”) increases the likelihood that affected pets will develop testicular tumors
  • Associated with male pseudohermaphrodism in miniature schnauzers; “pseudohermaphrodism” is a condition where the pet has either ovaries or testicles, but has uncertain (ambiguous) external genitalia

Skin Disorder due to Increased Levels of Androgen (Known as “Hyperandrogenism”) Associated with Testicular Tumors

  • Androgen-producing testicular tumors (especially interstitial cell tumors) in intact male dogs

Alopecia X

  • Hairs fail to cycle normally; an underlying hormonal cause has not been identified

Risk Factors

  • Intact male and female dogs are at increased risk for developing testicular tumors and ovarian cysts/tumors, respectively
  • Lack of normal descent of one or both testicles into the scrotum, resulting in the testicle(s) being located in the abdomen or inguinal canal (known as “cryptorchidism”) increases the likelihood that affected pets will develop testicular tumors
  • Administration of medications containing estrogen
  • Alopecia X—breed (miniature poodle and plush-coated breeds, such as the Pomeranian, chow chow, Akita, Samoyed, Keeshonden, Alaskan malamute, and Siberian husky)

Treatment

Health Care

  • Depends on cause of skin disorder
  • Discontinue administration of estrogen-containing medications, as directed by your veterinarian, if excessive estrogen is the likely cause of the skin disorder

Surgery

  • Skin biopsy
  • Surgical removal of testicles (neuter or castration) of pets with lack of normal descent of one or both testicles into the scrotum, resulting in the testicle(s) being located in the abdomen or inguinal canal (cryptorchidism); neuter when young
  • Surgical removal of testicles (neuter or castration)— testicular tumors
  • Exploratory surgery (known as a “laparotomy”)—diagnosis and treatment (such as surgical removal of the ovaries and uterus [spay or ovariohysterectomy] and surgical removal of testicles located in the abdomen [castration]) for ovarian cysts and tumors and abdominal testicular tumors
  • Alopecia X—surgical removal of reproductive organs (ovariohysterectomy in females and neuter or castration in males) may lead to hair regrowth in some dogs; hair regrowth may take up to 3 months before becoming evident

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive

General Treatment

  • Topical (applied to the skin directly) medication to treat seborrhea (known as “antiseborrheic therapy”)—conditions with associated keratinization defects and comedones (in which the hair follicles are filled with oils and skin cells)
  • Antibiotics—to treat associated skin infections, characterized by the presence of pus (pyodermas)

Alopecia X

  • Melatonin—hair regrowth can take up to 3 months to become evident; this treatment is effective in approximately 40% of affected dogs; should be tried following neutering; once hair growth has occurred, discontinue melatonin treatment
  • Other MedicationsConsider mitotane or o,p’-DDD (Lysodren) to stimulate hair regrowth in some dogs; can take up to 3 months for hair regrowth to become evident
  • Trilostane to stimulate hair regrowth in some dogs; can take up to 3 months for hair regrowth to become evident

Follow-Up Care

Patient Monitoring

  • Treatment with mitotane or o,p’-DDD (Lysodren)—bloodwork (electrolytes) and adrenocorticotropic hormone (ACTH)-stimulation testing regularly
  • Treatment with trilostane—bloodwork (electrolytes) and ACTH-stimulation testing regularly

Expected Coourse and Prognosis

  • Female increased levels of estrogen (hyperestrogenism)—improvement should occur within 3–6 months after surgical removal of the ovaries and uterus (spay or ovariohysterectomy)
  • Estrogen- and androgen-secreting tumors—resolution of signs noted within 3–6 months after surgical removal of the ovaries and uterus (spay or ovariohysterectomy) or the testicles (castration), respectively

Surgery

  • Biopsy of a tumor or the skin may be indicated in the diagnostic workup for some causes of hair loss (alopecia)
  • Hormonal disorders causing hair loss (treatment determined by specific hormonal disorder)—surgery may include removal of ovaries and uterus (known as “ovariohysterectomy” or “spay”), removal of testicles (known as “castration”), or removal of adrenal glands (known as “adrenalectomy”)
  • Surgical removal of skin cancer or tumors
  • Alopecia X–hair regrowth will occur only in some dogs, regardless of treatment; hair loss may recur in spite of continued treatment

Key Points

  • Alopecia X is a cosmetic condition, resulting in hair loss only; no cure has been determined to treat the hair loss; hair regrowth will occur only in some dogs regardless of treatment; hair loss may recur months to years later in spite of continued treatment

Hair Loss in Dogs (Canine Alopecia)

Hair Loss in Dogs (Canine Alopecia)–An Overview

  • “Alopecia” is the medical term for hair loss
  • Hair loss is a common disorder in dogs
  • Characterized by a complete or partial lack of hair in areas where it is present normally
  • Pattern of hair loss–varied or symmetrical
  • May be the primary problem or be secondary to an underlying cause
  • May be associated with a single cause or multiple causes

Signalment/Description of Pet

  • May be sudden (acute) in onset or slowly progressive
  • Multiple patches of circular hair loss (alopecia)—most frequently associated with inflammation of the hair follicles (known as “folliculitis”) from bacterial infection and/or demodectic mange (known as “demodicosis”)
  • Large, more widespread areas of hair loss (alopecia)—may indicate abnormal development of the hair follicles or hair (known as “follicular dysplasia”) or a more generalized disease
  • The pattern and degree of hair loss are important for establishing a diagnosis

Causes

Multiple Areas (Multifocal) of Hair Loss

  • Localized demodectic mange (demodicosis)—partial to complete hair loss (alopecia) with reddening of the skin (known as “erythema”) and mild scaling; lesions may become inflamed and may have dried discharge on the surface (dried discharge known as “crusts”)
  • Ringworm (known as “dermatophytosis”)—”ringworm” is a fungal infection on the surface of the skin characterized by partial to complete hair loss (alopecia) with scaling; with or without reddening of the skin (erythema); not always “ring-like” in appearance
  • Inflammation of the hair follicles due to Staphylococcus bacterial infection (known as “staphylococcal folliculitis”)—circular patterns of hair loss (alopecia) bordered by scales (accumulations of surface skin cells, such as seen in dandruff) or surface peeling of the skin (the pattern is known as an “epidermal collarette”), reddening of the skin (erythema), dried discharge on the surface of the skin lesion (crust), and darkened areas of skin (known as “hyperpigmented macules”)
  • Injection reactions—inflammation with hair loss (alopecia) and/or thinning of the skin (known as “cutaneous atrophy”) from scarring
  • Rabies-vaccine inflammation of the blood vessels (known as “vasculitis”)—well-demarcated patch of hair loss (alopecia) at the location where the rabies vaccine was administered is observed 2–3 months following vaccination
  • Localized scleroderma (condition in which normal skin is replaced by scar tissue for some unknown cause)—well-demarcated, shiny, smooth skin with hair loss (alopecia); lesion is a thickened, raised, flat-topped area that is slightly higher than the normal skin (known as a “plaque”)
  • Specific condition characterized by multiple patches of hair loss (known as “alopecia areata”)—non-inflammatory areas of complete hair loss (alopecia)
  • Condition characterized by multiple areas of hair loss with reddened skin, scales, and signs of itchiness (known as “pruritus”) with inflammation of the sebaceous glands, the glands that produce oils in the hair coat (condition known as “sebaceous adenitis”) seen in short-coated breeds—ring-like areas of hair loss (alopecia) and scaling

Symmetrical Hair Loss

  • Excessive levels of steroids produced by the adrenal glands (known as “hyperadrenocorticism” or “Cushing’s syndrome”)—hair loss along the sides of the body (known as “truncal alopecia”) associated with thin skin, plugs of keratin and oil in the follicles of the skin (known as “comedones”), and skin infection characterized by the presence of pus (known as “pyoderma”)
  • Inadequate levels of thyroid hormone (known as “hypothyroidism”)—hair loss (alopecia) is an uncommon presentation
  • Non-inflammatory hair loss (non-inflammatory alopecia, known as “alopecia X”)—symmetrical hair loss along the sides of the body (truncal alopecia) associated with darkened skin (known as “hyperpigmentation”); hair loss often starts along the collar area of the neck; seen in Pomeranians, chow chows, Akitas, Samoyeds, Keeshonden, Alaskan malamute, and Siberian husky
  • Excessive levels of estrogen (known as “hyperestrogenism”) in females—symmetrical hair loss (alopecia) of the flanks and skin between the external genitalia and the anus (perineal skin) and between the rear legs (inguinal skin) with enlarged external genitalia (vulva) and mammary glands
  • Inadequate secretion of female hormones (known as “hypogonadism”) in intact females—hair loss of the skin between the external genitalia and the anus (perineal skin), flank, and hair loss along the sides of the body (truncal alopecia)
  • Testosterone-responsive skin disorder (known as “testosterone-responsive dermatosis”) in castrated males—slowly progressive hair loss along the sides of the body (truncal alopecia)
  • Male feminization from Sertoli cell tumor (a type of tumor in the testicles)—hair loss (alopecia) of the skin between the external genitalia and the anus (perineal skin) and genital region with excessive development of the male mammary glands (known as “gynecomastia”)
  • Castration-responsive skin disorder (known as “castration-responsive dermatosis”)—hair loss (alopecia) in the collar area, rump, skin between the external genitalia and the anus (perineal skin), and flanks
  • Estrogen-responsive skin disorder (known as “estrogen-responsive dermatosis”) in spayed female dogs—hair loss (alopecia) of the skin between the external genitalia and the anus (perineal skin) and genital regions
  • Seasonal flank hair loss/cyclic flank hair loss (alopecia)—creeping hair loss involving the flanks with darkened skin (hyperpigmentation); seen in boxers, English bulldogs, and Airedale terriers

Patchy to Generalized (Diffuse) Hair Loss

  • Demodectic mange (demodicosis)—often associated with reddening of the skin (erythema), inflammation of the hair follicles (folliculitis), and darkened skin (hyperpigmentation)
  • Bacterial infection/inflammation of the hair follicles (folliculitis)—multiple areas of circular hair loss (alopecia) that may join to form large areas of hair loss; circular patterns of hair loss bordered by scales (accumulations of surface skin cells, such as seen in dandruff) or surface peeling of the skin (epidermal collarette)
  • Ringworm (dermatophytosis)—often accompanied by scales (accumulations of surface skin cells, such as seen in dandruff)
  • Sebaceous adenitis (condition characterized by multiple areas of hair loss with reddened skin, scales, and signs of itchiness [known as “pruritus”] with inflammation of the sebaceous glands, the glands that produce oils in the hair coat)—hair loss (alopecia) with thick, adherent scales; predominantly along the back line of the body, including the head
  • Color-mutant/dilution hair loss (alopecia)—thinning of the hair coat with secondary inflammation of the hair follicles (folliculitis) in some blue or fawn dogs
  • Abnormal development of the hair follicles or hair (known as “follicular dysplasia”)—slowly progressive hair loss (alopecia)
  • Hair loss during stages of the hair growth cycle—sudden (acute) onset of hair loss (alopecia)
  • Inadequate levels of thyroid hormone (hypothyroidism)—generalized (diffuse) thinning of the hair coat
  • Excessive levels of steroids produced by the adrenal glands (hyperadrenocorticism or Cushing’s disease)—hair loss along the sides of the body (truncal alopecia) with thin skin and formation of plugs of keratin and oil in the follicles of the skin (comedones)
  • Epitheliotropic lymphoma (type of cancer in the skin characterized by the presence of abnormal lymphocytes; a lymphocyte is a type of white-blood cell, formed in lymphatic tissue throughout the body)—widespread, generalized hair loss along the sides of the body (truncal alopecia) with scales (accumulations of surface skin cells, such as seen in dandruff) and reddening of the skin (erythema); later small, solid masses (known as “nodules”) and thickened, raised, flat-topped areas that are slightly higher than the normal skin (known as “plaques”) may form
  • Pemphigus foliaceus (a disease in which the body’s immune system attacks its own skin)—hair loss (alopecia) associated with the formation of scales (accumulations of surface skin cells, such as seen in dandruff) and dried discharge on the skin lesions (crusts)
  • Keratinization disorders (disorders in which the surface of the skin is abnormal)—hair loss (alopecia) associated with excessive scales (accumulations of surface skin cells, such as seen in dandruff) and greasy surface texture

Specific Locations of Hair Loss

  • Hair loss involving the ears (pinnal alopecia) or pattern baldness—miniaturization of hairs and progressive hair loss (alopecia); seen in dachshunds, greyhounds, American water spaniels, Portuguese water spaniels, Boston terriers, Manchester terriers, whippets, Italian greyhounds, Chihuahuas
  • Traction hair loss (alopecia)—hair loss on the top and sides of the head secondary to having barrettes or rubber bands applied to the hair
  • Post-clipping hair loss (alopecia)—failure to regrow hair after clipping; may be associated with disruption of the hair-growth cycle
  • Melanoderma (hair loss [alopecia] of Yorkshire terriers)—symmetrical hair loss with darkened skin of the ears, bridge of the nose, tail, and feet
  • Seasonal flank hair loss/cyclic flank hair loss (alopecia)—creeping hair loss of the flanks with darkened skin (hyperpigmentation); seen in boxers, English bulldogs, and Airedale terriers
  • Abnormal development of the hair follicles or hair involving black hairs only (known as “black hair follicular dysplasia”)—hair loss (alopecia) involving only the black-haired areas of the body
  • Inherited inflammatory disorder that affects the skin and muscles of unknown cause (condition known as “idiopathic familial canine dermatomyositis”) in collies and Shetland sheepdogs—hair loss (alopecia) of the face, tip of ears, tail, and digits; associated with scales (accumulations of surface skin cells, such as seen in dandruff) and dried discharge on the skin lesions (crusts), and scarring

Treatment

Health Care

  • Demodectic mange (demodicosis)—amitraz, ivermectin, milbemycin
  • Ringworm (dermatophytosis)—griseofulvin, ketoconazole, itraconazole, lime sulfur dips, terbinafine
  • Inflammation of hair follicles due to Staphylococcus bacterial infection (staphylococcal folliculitis)—shampoo and antibiotic therapy
  • Sebaceous adenitis (condition with hair loss, reddened skin, scales and inflammation of the oil-secreting sebaceous glands)—keratolytic shampoo, essential fatty acid supplementation, retinoids
  • Keratinization disorders (disorders in which the surface of the skin is abnormal)—shampoos, retinoids, vitamin D, cyclosporine

Surgery

  • Biopsy of a tumor or the skin may be indicated in the diagnostic workup for some causes of hair loss (alopecia)
  • Hormonal disorders causing hair loss (treatment determined by specific hormonal disorder)—surgery may include removal of ovaries and uterus (known as “ovariohysterectomy” or “spay”), removal of testicles (known as “castration”), or removal of adrenal glands (known as “adrenalectomy”)
  • Surgical removal of skin cancer or tumors

Medications

  • Vary with specific cause
  • Excessive levels of steroids produced by the adrenal glands (hyperadrenocorticism or Cushing’s syndrome)—mitotane (Lysodren), trilostane

Follow-Up Care

Patient Monitoring

  • Determined by specific cause

Preventions and Avoidance

  • Determined by specific cause

Possible Complications

  • Determined by specific cause

Expected Course and Prognosis

  • Determined by specific cause

Key Points

  • “Alopecia” is the medical term for hair loss
  • Hair loss is a common problem in dogs
  • Pattern of hair loss varies–may be localized or widespread
  • Skin itself may appear normal or may be abnormal

Risk Factors

  • Intact male
  • Co-existing behavioral problem, such as separation anxiety
  • Owners poorly informed or motivated to properly housetrain their dog

Flea Bite Hypersensitivity & Flea Control

Flea Bite Hypersensitivity & Flea Control – Overview

  • “Hypersensitivity” is an increased sensitivity or reaction in the skin due to the presence of a foreign substance; in flea-bite hypersensitivity, the foreign substance is found in flea saliva; the reaction is immune based and would be considered to be an “allergic” reaction
  • “Dermatitis” is the medical term for inflammation of the skin
  • “Antigens” are substances that induce sensitivity or immune response
  • “Flea-bite hypersensitivity”—hypersensitivity or allergic reaction to antigens in flea saliva, with or without evidence of fleas and flea dirt
  • “Flea-bite dermatitis”—inflammation of the skin due to the flea bite itself; it is not an allergic or hypersensitivity reaction, but rather an irritant response to flea bites

Genetics

  • Flea-bite hypersensitivity—unknown inheritance pattern; more common in breeds with atopy (disease in which the pet is sensitized [or “allergic”] to substances found in the environment [such as pollen] that normally would not cause any health problems)

Signalment/Description of Pet

Species

  • Dogs
  • Cats

Mean Age and Range

  • Flea-bite hypersensitivity—rare in pets less than 6 months of age; average age range, 3–6 years, but may be seen at any age

Signs/Observed Changes in the Pet

  • Determined by the severity of the reaction and the degree of exposure to fleas (that is, seasonal or year-round)
  • Itchiness (known as “pruritus”)
  • Compulsive biting
  • Chewing (“corncob nibbling”)
  • Licking, primarily in the back half of the body, but may include the areas
  • Signs of fleas and flea dirt; finding fleas and flea dirt is beneficial, although not essential, for the diagnosis of flea-bite hypersinsitivity
  • Sensitive pets require a low exposure to fleas to have an immune response and they tend to over groom, removingt evidence of flea infestation, and making identification of parasites difficult
  • Hair loss (known as “alopecia”)
  • Small, raised skin lesions (known as “papules”)
  • Darkened skin (known as “hyperpigmentation”) in dogs
  • Thickening and hardening of the skin, usually associated with hyperpigmentation (known as “lichenification”) in dogs
  • “Hot spots” in dogs
  • Miliary dermatitis (skin inflammation characterized by numerous, small, crusty bumps) in cats)

Causes

  • Fleas
  • Immune response to flea saliva (flea-bite hypersensitivity or flea-allergy dermatitis)

Risk Factors

  • Flea-bite hypersensitivity—intermittent exposure to fleas increases likelihood of development; commonly seen in conjunction with atopy (disease in which the pet is sensitized [or “allergic”] to substances found in the environment [such as pollen] that normally would not cause any health problems)

Treatment

Health Care

  • Outpatient treatment

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

  • Steroids—to decrease inflammation in the skin for symptomatic relief, while instituting flea control
  • Antihistamines–symptomatic relief
  • Flea control on the pet; examples include dinotefuran/pyriproxyfen (monthly spot treatment; rapid acting; two products—one for cats and one for dogs; dog product contains high dose of the insecticide, permethrin, and should NOT be used on cats); fipronil (monthly spot treatment for dogs and cats and spray treatment for dogs); imidacloprid (monthly spot treatment for cats and dogs); metaflumizone (monthly spot treatment for dogs or cats; product for dogs contains another active ingredient [amitraz] and should not be used on cats)
  • Flea control using medications given by mouth (known as “oral medications”)—nitenpyram (rapid action, but short-acting; kills over 95% of adult fleas on dogs and cats within 4–6 hours of administration, lasts for 48–72 hours); spinosad (monthly oral treatment for dogs only)
  • Other flea control for pets (such as flea sprays and other topical treatments)—usually contain pyrethrins and pyrethroids (synthetic pyrethrins) with an insect-growth regulator or synergist; generally effective for less than 48–72 hours
  • Environmental/indoor treatment—professional exterminator or home-use fogs and premises sprays; products usually contain organophosphates, pyrethrins, and/or insect-growth regulators; apply according to manufacturer’s directions; treat all areas of the house
  • Environmental/indoor treatment using inert substances—boric acid, diatomaceous earth, and silica aerogel; treat every 6–12 months; follow manufacturer’s recommendations
  • Environmental/outdoor treatment—concentrate outdoor treatment in shaded areas; sprays usually contain pyrethroids or organophosphates and an insect-growth regulator; a product containing nematodes (Steinerma carpocapsae) is chemical-free
  • Other products for use include flea powders, dips, sprays, and foams
  • NOTE: Always read all label instructions and follow the manufacturer’s directions when using any flea-control product; ensure that the product is labeled for use on the species (dog or cat) or location (indoors or outdoors) for which you intend to apply it—for example, some products that are safe for dogs are very toxic to cats and should not be used on cats

Follow-Up Care

Patient Monitoring

  • Itchiness (pruritus)—a decrease in itchiness indicates the flea infestation and/or flea-bite hypersensitivity is being controlled
  • Fleas and flea dirt—absence is not always a reliable indicator of successful treatment in very sensitive pets

Preventions and Avoidance

  • Year-round warm climates—year-round flea control is required
  • Seasonally warm climates–begin flea control in May or June, as directed by your pet’s veterinarian

Possible Complications

  • Secondary bacterial infections
  • Sudden (acute) moist dermatitis, also known as “hot spots”
  • Acral lick dermatitis (inflammation of the skin characterized by a firm, ulcerated lesion on a leg, caused by consistant licking)

Expected Course and Prognosis

  • Prognosis is good, if strict flea control is instituted

Key Points

  • Flea control is important for dogs and cats
  • No cure exists for flea-bite hypersensitivity
  • Flea-allergic pets often become more sensitive to flea bites as they age
  • Controlling exposure to fleas is currently the only means of controlling signs; “allergy shots” (known as “hyposensitization”) for flea-bite hypersensitivity are not effective

Exfoliative Dermatoses

Exfoliative Dermatoses – An Overview

  • Excessive or abnormal shedding of skin cells, resulting in the clinical presentation of accumulations of surface skin cells, such as seen in dandruff (known as “scales”)
  • “Exfoliative” refers to the detachment and shedding of surface skin cells; “dermatosis” (plural, “dermatoses”) is the medical term for any skin abnormality or disorder
  • “Primary” refers to a condition that occurs first in the skin; “secondary” refers to changes that occur following the primary disease—for example, the skin may be inflamed due to a nutritional deficiency (primary condition) and become infected by bacteria invading the inflamed skin (secondary condition) or the skin changes are secondary to the presence of some other problem or abnormality (such as the presence of parasites on the skin)

Signalment/Description of Pet

Species

  • Dogs
  • Cats

Breed Predilections

  • Primary exfoliative dermatoses—cocker spaniels, English springer spaniels, West Highland white terriers, basset hounds, Doberman pinschers, Irish setters, Labrador retrievers, Siberian huskies, Alaskan malamutes, dachshunds, chow chows, Yorkshire terriers, poodles, Great Danes, whippets, salukis, Italian greyhounds, standard poodles, Samoyeds, Akitas, vizslas, golden retrievers
  • Primary seborrhea (excessively oily or dry scaling of the skin)—Persian kittens
  • Secondary exfoliative dermatoses—any breed of dog or cat

Mean Age and Range

  • Primary exfoliative dermatoses—apparent by 2 years of age
  • Primary seborrhea (excessively oily or dry scaling of the skin)—newborn Persian kittens
  • Secondary exfoliative dermatoses—any age

Signs/Observed Changes in the Pet

  • Excessive scaling
  • Smelly or malodorous skin; “rancid fat” odor is common
  • Itchiness (known as “pruritus”)
  • Oily skin and hair
  • Dry or greasy accumulations of surface skin cells, as seen in dandruff (scales); accumulations may be fine or coarse; may be located throughout the hair coat or in localized areas
  • Hair follicles may become filled with oil and skin cells (known as “comedones”)
  • Accumulation of debris that adheres to hair shaft (known as “follicular casts”)
  • “Candle wax”–like deposits on hair
  • Hair loss (known as “alopecia”)
  • Secondary skin inflammation, caused by the yeast Malassezia (known as “secondary Malassezia dermatitis”)

Causes and Risk Factors

Primary Exfoliative Dermatoses

  • Primary excessively dry or oily scaling of the skin (known as “seborrhea”) of unknown causes (so-called “idiopathic seborrhea”) that is a primary disorder in the normal replacement and shedding of skin cells (known as a “keratinization disorder”)—breeds at highest risk: cocker spaniels, English springer spaniels, West Highland white terriers, basset hounds, Doberman pinschers, Irish setters, and Labrador retrievers; dry (known as “seborrhea sicca”) and greasy or oily (known as “seborrhea oleosa”) forms exist, but determination of type has little prognostic value
  • Skin disorder that responds to treatment with vitamin A (known as “vitamin A–responsive dermatosis”)—nutritionally responsive; seen primarily in young cocker spaniels; clinical signs similar to severe idiopathic seborrhea; distinguished by response to dietary vitamin A supplementation
  • Skin disorder that responds to treatment with zinc (known as “zinc-responsive dermatosis”)—nutritionally responsive; results in hair loss (alopecia); accumulations of surface skin cells, as seen in dandruff (scales); dried discharge on the surface of the skin lesion (known as a “crust”); and reddening of the skin (known as “erythema”) around the eyes, ears, feet, lips, and other external orifices; two syndromes are seen: (1) young adult dogs, especially Siberian huskies and Alaskan malamutes, and (2) rapidly growing, large-breed puppies
  • Abnormalities in the development of the skin and related structures (such as hair follicles)—abnormal development of the hair follicles or hair (known as “follicular dysplasia”); seen as hair loss (alopecia) in color mutant or dilution pets; represent abnormalities in deposition of melanin pigments (responsible for the color of the skin and hair) of the hair shaft and structural hair growth; breeds commonly affected: blue and fawn Doberman pinschers, Irish setters, dachshunds, chow chows, Yorkshire terriers, poodles, Great Danes, whippets, salukis, and Italian greyhounds; signs include failure to regrow blue or fawn hair with normal “point” hair growth, excessive accumulations of surface skin cells, as seen in dandruff (scales), hair follicles filled with oil and skin cells (comedones), and skin infection characterized by the presence of pus (secondary pyoderma)
  • Thickening of the skin (known as “hyperkeratosis”) of the nose and pads of the feet of unknown cause (so-called “idiopathic nasodigital hyperkeratosis”)—excessive accumulation of surface skin cells (scales) and dried discharge on the surface of the skin lesion (crusts) on the tough, hairless skin of the nose (known as the “nasal planum”) and footpad margins; possibly an aging change, seen in spaniels and Labrador retrievers; may result in cracking and secondary bacterial infection that can be quite painful
  • Inflammation of the sebaceous glands, the glands that produce oils in the hair coat (condition known as “sebaceous adenitis”)—inflammatory disease; may be of unknown cause (so-called “idiopathic sebaceous adenitis”); three specific syndromes seen: (1) middle-aged standard poodles and Samoyeds—characteristic patchy or widespread (diffuse) hair loss (alopecia) and excessive accumulation of surface skin cells, as seen in dandruff (scales); accumulation of debris that adheres to hair shaft (follicular casts); most dogs are healthy; (2) Akitas—frequently develop severe and deep bacterial skin infection characterized by the presence of pus (pyoderma); (3) vizslas—disease appears distinctly different and is characterized by the presence of nodular, inflammatory lesions (known as “granulomas”); other breeds can be affected but are less likely than the breeds indicated previously
  • Abnormal development of the top surface of the skin (known as the “epidermis”; condition known as “epidermal dysplasia”) and congenital (present at birth) disorders of the normal replacement and shedding of skin cells (keratinization disorder; condition known as “ichthyosis”)—rare and severe congenital disorder of keratinization; reported in West Highland white terriers and golden retrievers; generalized accumulations of surface skin cells, as seen in dandruff (scales) and dried discharge on the surfaces of the skin lesions (crusts) at an early age; secondary bacterial and yeast infections are common
  • Primary excessively oily scaling of the skin (primary seborrhea)—newborn Persian kittens

Secondary Exfoliative Dermatoses

  • Increased sensitivity or reaction in the skin to the presence of a foreign agent (known as “cutaneous hypersensitivity”)—atopy (disease in which the pet is sensitized [or “allergic”] to substances found in the environment [such as pollen] that normally would not cause any health problems); flea-bite allergy; food allergy; and inflammation of the skin secondary to contact with some substance to which the pet reacts or to which the skin becomes irritated (known as “contact dermatitis”); characterized by itchiness (pruritus) and secondary skin trauma and irritation
  • Parasites of the skin—sarcoptic mange or scabies; demodectic mange (demodicosis) and “walking dandruff” (cheyletiellosis)
  • Skin infection characterized by the presence of pus (pyoderma)
  • Bacterial infection of the hair follicles (known as “bacterial folliculitis”)
  • Skin inflammation due to Malassezia, a yeast
  • A fungal infection affecting the skin, hair, and/or nails (known as “dermatophytosis”)
  • Hormonal disorders (known as “endocrinopathies”)—inadequate production of thyroid hormone (known as “hypothyroidism”) and excessive production of steroids by the adrenal glands (known as “hyperadrenocorticism” or “Cushing’s syndrome”) commonly produce excessive accumulation of surface skin cells, as seen in dandruff (scales); secondary skin infection characterized by the presence of pus (secondary pyoderma) common in both syndromes; other hormonal abnormalities (such as sex-hormone abnormalities, excessive production of thyroid hormone [known as “hyperthyroidism”], and diabetes mellitus [“sugar diabetes”]) also may be associated with excessive scaling
  • Age—senior pets may have a dull, brittle, and scaly hair coat; changes may be caused by natural alterations associated with aging; no specific defect identified
  • Nutritional disorders—skin disorders may occur with malnutrition and feeding generic dog food; result in accumulation of surface skin cells, as seen in dandruff (scales) from abnormalities in the normal replacement and shedding of skin cells (keratinization)
  • Diseases in which the body’s immune system attacks its own skin (known as “autoimmune skin diseases”)—pemphigus complex; cutaneous and systemic lupus erythematosus; often see areas of hair loss (alopecia) and scaling
  • Tumors, cancer, and precancerous disorders of the skin—may produce hair loss (alopecia) and accumulation of surface skin cells, as seen in dandruff (scales) when skin is damaged
  • Miscellaneous—any disease process may result in excessive accumulation of surface skin cells, as seen in dandruff (scales)
  • Exfoliative disorders (“exfoliative” refers to the detachment and shedding of surface skin cells)—rare in cats; include tail-gland hyperplasia or “stud tail,” in which the sebaceous glands at the base of the tail enlarge and overproduce oil secretions, leading to matted hair and scales in the hair coat; exfoliative skin inflammation (known as “exfoliative dermatitis”) associated with thymoma, a type of tumor of the thymus (the thymus is an organ located in the front of the chest, near the neck; it is part of the immune system)

Treatment

Health Care

  • Diagnose and control all treatable primary and secondary diseases
  • Frequent and appropriate treatment applied to the skin directly (known as “topical therapy”)—cornerstone of proper treatment
  • Frequent baths, as directed by your pet’s veterinarian
  • Recurrence of secondary infections may require repeated treatment and further diagnostic testing
  • Maintaining control of these skin disorders is often a lifelong commitment

Diet

  • Depends on underlying cause
  • Dietary modification may be necessary for cases of suspected food allergy and for nutritionally related skin disorders

Surgery

  • Skin biopsy may be necessary to determine diagnosis
  • Surgical removal of skin tumors/cancer

Medications

  • MMedications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive:

Treatment Applied to the Skin Directly (Topical Therapy)

Shampoos

  • Contact time of shampoo (that is, shampoo must be left on body for a certain amount of time)—5–15 minutes generally required, as directed by your pet’s veterinarian
  • Hypoallergenic shampoo—useful only in mild cases of dry scale and to maintain skin condition after the primary disease has been controlled
  • Sulfur/salicylic acid–containing shampoos—soften and loosen crusts and scales on the skin (known as “keratolytic shampoos”) and slow the growth of bacteria (known as a “bacteriostatic property”); excellent first choice for the moderately scaly pet; not overly drying
  • Benzoyl peroxide shampoo—strong action to soften and loosen crusts and scales on the skin (keratolytic shampoo), destroys bacteria or slows their growth and multiplication (known as an “antimicrobial property”), and flushes out the hair follicles; may cause irritation and severe dryness; frequently used for recurrent bacterial infection and/or extreme greasiness
  • Ethyl lactate shampoo—less effective than benzoyl peroxide for flushing out the hair follicles and not as effective against bacteria, but not as irritating or drying; most useful for moderate bacterial infection of the hair follicles (bacterial folliculitis) and dry scale
  • Chlorhexidine—a chemical antiseptic (compounds that kill or slow the growth of bacteria and other microorganisms); mildly drying; useful for moderate bacterial infections of the hair follicles (bacterial folliculitis) and skin inflammation caused by the yeast Malassezia (Malassezia dermatitis)
  • Tar shampoos—soften and loosen crusts and scales on the skin (keratolytic shampoos) and decrease itchiness (known as an “antipruritic property”); less degreasing than benzoyl peroxide; use for moderate scale associated with itchiness (pruritus); can be irritating; might be a substance linked to cancer (known as a “carcinogen”); not widely available in veterinary products

Moisturizers

  • Excellent for restoring skin hydration (frequent shampooing may result in excessive dryness and itchiness [pruritus]) and increasing effectiveness of subsequent shampoos
  • Humectants (moisturizers that attract water into the surface of the skin)—enhance hydration of the skin; at high concentrations may soften and loosen crusts and scales on the skin
  • Propylene glycol spray (50–75% dilution with water) applied frequently as directed by your pet’s veterinarian
  • Microencapsulation (moisturizers are placed in tiny capsules that allow prolonged effect)—may improve the residual activity of moisturizers by permitting sustained release after bathing
  • Emollients (agents that soften and soothe the skin)—coat the skin; smooth the roughened surfaces produced by excessive scaling

Generalized (Systemic) Therapy

  • Specific causes of exfoliative dermatoses require specific treatments (such as thyroid hormone [thyroxine] replacement for pets with inadequate levels of thyroid hormone [hypothyroidism]; zinc supplements for zinc-responsive dermatosis)
  • Antibiotics administered by mouth or injection—always indicated for secondary skin infection characterized by the presence of pus (secondary pyoderma)
  • Retinoid drugs—varied success for seborrhea of unknown cause (idiopathic seborrhea) or primary seborrhea; reports of individual response to retinoids in pets that do not respond to other treatments (known as “refractory” cases); very strict regulations have made it difficult to prescribe and dispense synthetic retinoids
  • Cyclosporine (medication to decrease the immune response) may be used in some cases
  • Ketoconazole (an antifungal drug)—may be used for treatment of severe skin inflammation due to Malassezia, a yeast

Follow-Up Care

Patient Monitoring

  • Antibiotics and treatment applied to the skin directly (topical therapy)—monitor response every 3 weeks; pets may respond differently to the various topical therapies
  • Seasonal changes, development of additional diseases (especially increased sensitivity or reaction in the skin to the presence of a foreign agent [cutaneous hypersensitivity]), and recurrence of skin infection characterized by the presence of pus (pyoderma)—may cause previously controlled pets to worsen; reevaluation critical for determining if new factors are involved and if changes in therapy are necessary
  • Hormonal disorders (endocrinopathies)—bloodwork to monitor thyroid levels following treatment for inadequate levels of thyroid hormone (hypothyroidism), should be performed 4–6 hours following administration of thyroid medication—frequency of thyroid monitoring as recommended by your pet’s veterinarian; adrenocorticotropic hormone (ACTH)-stimulation tests should be performed for proper management of pets with excessive production of steroids by the adrenal glands (hyperadrenocorticism or Cushing’s disease)
  • Some autoimmune disorders—reevaluate frequently during the initial phase of treatment; less often after remission
  • Medications to decrease the immune response (known as “immunosuppressive therapy”)—frequent bloodwork (such as complete blood counts [CBCs] and serum chemistries) and urinalyses with bacterial culture to monitor for complications
  • Retinoid drugs—bloodwork (serum chemistries, including triglycerides); Schirmer tear tests to monitor the eyes for changes in tear production
  • Ketoconazole—bloodwork (serum chemistries)

Preventions and Avoidance

  • Depend on underlying cause

Possible Complications

  • Depend on underlying cause

Expected Course and Prognosis

  • Depend on underlying cause

Key Points

  • Some causes of excessive or abnormal shedding of skin cells, resulting in the clinical presentation of accumulations of surface skin cells (such as dermatophytosis and several parasitic skin diseases), have either zoonotic potential or the ability to produce lesions in people; “potential zoonoses” are diseases that can be passed from animals to people
  • Diagnose and control all treatable primary and secondary diseases
  • Frequent and appropriate treatment applied to the skin directly (known as “topical therapy”)—cornerstone of proper treatment
  • Frequent baths, as directed by your pet’s veterinarian
  • Recurrence of secondary infections may require repeated treatment and further diagnostic testing
  • Maintaining control of these skin disorders is often a lifelong commitment

Eosinophilic Granuloma in Dogs & Cats

Eosinophilic Granuloma in Dogs & Cat – Overview

  • Cats—“eosinophilic granuloma complex” often is a confusing term for four distinct syndromes: (1) “eosinophilic plaque” (circumscribed, raised, round to oval lesions that frequently are ulcerated; usually located on the abdomen or thighs; lesions contain a type of white blood cell, called an eosinophil); (2) “eosinophilic granuloma” (a mass or nodular lesion containing eosinophils; usually found on the back of the thighs, on the face, or in the mouth); (3) “indolent ulcer” (circumscribed, ulcerated lesions; most frequently found on upper lip); (4) allergic miliary dermatitis (skin inflammation characterized by numerous, small, crusty bumps); the four syndromes are grouped together as “eosinophilic granuloma complex” primarily according to their clinical similarities, their frequent simultaneous development and tendency to recur, and their positive response to treatment with steroids
  • Dogs—”eosinophilic granulomas” are rare; not part of the eosinophilic granuloma complex; specific differences from cats are presented in the following information
  • “Eosinophilic” refers to eosinophils, a type of white-blood cell usually involved in allergic responses
  • “Granuloma” is a large inflammatory nodule or solid mass
  • “Complex” is a group of signs or diseases that have an identifiable characteristic that makes them similar in some fashion

Genetics

  • Several reports of related affected individuals and a study of disease development in a colony of cats indicate that, in at least some individuals, genetic susceptibility (perhaps resulting in an inheritable dysfunction of eosinophils) is a significant component for the development of the eosinophilic granuloma and indolent ulcer

Signalment/Description of Pet

Species

  • Cats–eosinophilic plaque, eosinophilic granuloma, indolent ulcer, and allergic military dermatitis
  • Dogs–eosinophilic granuloma

Breed Predilections

  • Cats–none
  • Eosinophilic granuloma in dogs—Siberian huskies (76% of cases), Cavalier King Charles spaniels, possibly German shepherd dogs

Mean Age and Range

  • Eosinophilic plaque (circumscribed, raised, round to oval lesions that frequently are ulcerated; usually located on the abdomen or thighs; lesions contain a type of white blood cell, called an eosinophil)—2–6 years of age
  • Genetically initiated eosinophilic granuloma–less than 2 years of age
  • Allergic disorder–over 2 years of age
  • Eosinophilic granuloma in dogs–usually less than 3 years of age

Predominant Sex

  • Cats—females may be more likely to develop one or more of the syndromes of eosinophilic granuloma complex than are males
  • Eosinophilic granuloma in dogs–males (72% of cases)

Signs/Observed Changes in the Pet

Cats

  • Distinguishing among the syndromes depends on both clinical signs and microscopic findings
  • Lesions of more than one syndrome may occur simultaneously; lesions of all four syndromes may develop spontaneously and suddenly (acutely)
  • Development of eosinophilic plaques (circumscribed, raised, round to oval lesions that frequently are ulcerated; usually located on the abdomen or thighs; lesions contain a type of white blood cell, called an eosinophil) may be preceded by periods of sluggishness (lethargy)
  • A seasonal incidence is possible
  • Signs vary in intensity—they may increase and decrease over time (known as a “waxing and waning” course)
  • Eosinophilic plaque—loss of hair (known as “alopecia”), reddened skin (known as “erythema”), patches of loss of superficial layers of skin (known as “erosive patches”) or well-demarcated, steep-walled thickened, raised, flat-topped areas that are slightly higher than normal skin (known as “plaques”); usually occur in the inguinal or perineal (area between the anus and external genitalia) areas, along the thighs, lower abdomen, and under the front legs, near the chest; frequently moist or glistening; may have enlarged lymph nodes near the area of the eosinophilic plaques
  • Eosinophilic granuloma (mass or nodular lesion containing eosinophils)—occur as (1) a distinctly linear orientation (“linear granuloma”) on the back part of the thigh; (2) an individual lesion or multiple lesions that are coming together, located anywhere on the body; ulcerated with a “cobblestone” or coarse pattern; white or yellow, possibly representing collagen degeneration; (3) lip margin and chin swelling (“pouting”); (4) footpad swelling, pain, and lameness (most common in cats under 2 years of age); (5) ulcers of the mouth (especially on the tongue, palate, and palatine arches)—cats with ulcers of the mouth may have difficulty swallowing (known as “dysphagia”), have bad breath (known as “halitosis”), and may drool
  • Lesion development may stop spontaneously in some cats, especially with the inheritable form of eosinophilic plaque
  • Allergic military dermatitis (skin inflammation characterized by numerous, small, crusty bumps)—multiple brown/black crusted and reddened, small, raised bumps (known as “papules”); lesions more often felt than seen; may be associated with hair loss (known as “alopecia”); usually itchy (known as “pruritus”); lesions frequently felt/seen along the back of the cat
  • Idolent ulcer–classically concave and firm or hardened ulcerations with a granular, orange-yellow color, confined to the upper lips

Dogs

  • Eosinophilic granuloma–ulcerated, thickened, raised, flat-topped areas that are slightly higher than normal skin (plaques) and masses; dark or orange color; most often affects the tongue and the folds of moist tissue extending from the soft palate to the side of the tongue (known as the “palatine arches”); skin lesions on the prepuce and flanks have been reported

Causes

  • Allergy—flea or insect (such as mosquito-bite) allergy, food allergy, and atopy (disease in which the pet is sensitized [or “allergic”] to substances found in the environment [such as pollen] that normally would not cause any health problems)
  • Inherited dysfunction or eosinophils is a possible cause
  • Eosinophilic granuloma in dogs—unknown cause; genetic susceptibility in certain breeds; increased sensitivity or reaction in the skin to the presence of a foreign material (known as “hypersensitivity”) often suspected (such as to an insect bite) in breeds that do not have a genetic susceptibility

Treatment

Health Care

  • Most pets treated as outpatients, unless severe disease of the mouth prevents adequate fluid intake
  • Identify and eliminate offending allergen(s) before providing medical intervention; “allergens” are substances to which the pet has developed an allergy
  • “Allergy shots” (known as “hyposensitization”) in cats that have tested positive on skin tests for allergies–successful in a majority of cases; preferable to long-term steroid administration
  • Avoid excessive grooming, which may damage the skin lesions

Activity

  • No restrictions

Diet

  • No restrictions, unless a food allergy is suspected

Surgery

  • Skin biopsy to obtain samples for microcopic evaluation of lesions
  • Surgical removal of a lesion may be performed in some cases
  • Eosinophilic granuloma in dogs–individual lesions may be removed surgically if they are being traumatized or are not responsive to medical treatment

Medications

Medications presented in this section are intended to provide general information about possible treatment. The treatment for a particular condition may evolve as medical advances are made; therefore, the medications should not be considered as all inclusive.

Eosinophilic Granuloma Complex in Cats

  • Eosinophilic plaque (circumscribed, raised, round-to-oval lesions that frequently are ulcerated) and eosinophilic franuloma (a mass or nodular lesion containing eosinophils)
  • Antibiotics—trimethoprim-sulfadiazine, cephalexin, amoxicillin-clavulanate, clindamycin; effective in some cats
  • Injectable methylprednisolone—most common treatment; not recommended for long-term treatment as response to medication may decrease with repeated treatments
  • Steroids—ongoing treatment with prednisolone required to control lesions; other drugs: dexamethasone and triamcinolone
  • Fluocinolone (a steroid) and dimethyl sulfoxide (DMSO; Synotic lotion)—apply to individual skin lesions (known as “topical treatment”); not practical for cats with many lesions and may cause side effects in these cats
  • Indolent ulcer (circumscribed, ulcerated lesions; most frequently found on upper lip)
  • Steroids administered by injection or by mouth
  • ?-Interferon-administered daily in cycles of 7 days on, 7 days off; limited success; effective in some cats
  • Antibiotics–trimethoprim-sulfadiazine, cephalexin, or amoxicillin-clavulanate; effective in some cats
  • Other therapies
  • Chlorambucil, a chemoterapeutic drug
  • ?-Interferon
  • Megestrol acetate–not recommended because of the severity of possible side effects; however, may be tried in cats that do not respont to any other treatment

Eosinophilic Granuloma in Dogs

  • Steroids administered by mouth–prednisone
  • Injection of steroids into the lesions–methylprednisolone

Follow-Up Care

Patient Monitoring

  • Pets receiving steroids—baseline and follow-up bloodwork (complete blood counts [CBCs] and serum chemistry profiles) and urinalyses with bacterial culture and sensitivity testing of urine
  • Pets receiving medications to decrease the immune response (known as “immunosuppressive drugs”)—frequent CBCs (biweekly at first, then monthly or bimonthly as therapy continues) to monitor for bone-marrow suppression leading to low red-blood cell and low white-blood cell counts; routine serum chemistry profiles and urinalyses with bacterial culture and sensitivity testing of urine (monthly at first, then every 3 months) to monitor for complications (such as kidney disease, diabetes mellitus, and urinary tract infection)

Expected Course and Prognosis

  • Lesions should resolve permanently if a primary cause can be identified and controlled. Most lesions increase and decrease over time (wax and wane), with or without therapy; thus an unpredictable schedule of recurrence should be anticipated
  • Drug dosages should be tapered to the lowest possible level (or discontinued, if possible), once the lesions have resolved; changes in drug dosage should be at the direction of your pet’s veterinarian
  • Lesions in cats with the inheritable disease may resolve spontaneously after several years
  • Eosinophilic granuloma in dogs—may not respond to medical treatment

Key Points

  • Possible allergice or inherited causes
  • Most lesions increase and decrease over time (wax and wane), with or without therapy; thus an unpredictable schedule of recurrence should be anticipated
  • In some cases, a decision may be made to postpone medical intervention, unless severe lesions develop