Inflamed Skin & Allergies

Inflamed Skin & Allergies – An Overview

Overview

  • “Atopic” refers to “atopy”; “atopy” is another name for atopic dermatitis
  • “Dermatitis” is the inflammation of the skin
  • “Allergy” is an altered state of immune response to a foreign substance; “allergen” is a substance to which the pet has developed an allergy
  • Atopic dermatitis is a form of skin inflammation due to a hypersensitivity reaction of the pet to normally harmless or innocuous substances, such as pollens (grasses, weeds, and trees), molds, house-dust mites, skin (epithelial) allergens, and other environmental allergens
  • The skin inflammation (dermatitis) is long term (chronic) and relapses are common; it is not contagious and is characterized by itchiness (known as “pruritus”)

Genetics

  • Dogs–inherited susceptibility; however, the mode of inheritance is unknown and environmental influences are important
  • Cats–unclear

Signalment/Description of Pet

Species

  • Dogs
  • Cats

Breed Predilections

  • Dogs–any breed, including mixed-breed dogs, may be affected, recognized more frequently in certain breeds or families of dogs, which can vary geographically
  • In the United States, commonly affected dog breeds include the Boston Terrier, Cairn Terrier, Dalmatian, English Bulldog, English Setter, Irish Setter, Lhasa Apso, Miniature Schnauzer, Pug, Sealyham Terrier, Scottish Terrier, West Highland White Terrier, Wirehaired Fox Terrier, and Golden Retriever
  • Cats–no breed appears to be more likely to develop allergic skin disease (atopic dermatitis)

Mean Age and Range

  • Dogs–mean age at onset of signs is 1-3 years; range 3 months-6 years of age; signs may be mild the first year, but usually progress and become clinically apparent before 3 years of age

Predominant Sex

  • Both sexes are probably effected equally

Signs/Observed Changes in the Pet

  • “Itching” as demonstrated by scratching, rubbing, and/or licking (itchiness is known as “pruritus”)
  • Most skin changes caused by self-induced trauma (scratching, rubbing, licking, biting at skin)
  • Areas of the face, feet, and under the front legs are affected commonly
  • Signs may be seasonal initially
  • Recurring skin and/or ear infections (may be bacterial and/or yeast infection)
  • May have temporary response to steroids
  • Signs progressively worsen with time
  • Lesions–vary from none to broken hairs or saliva discoloration of the hairs (giving a rust-brown appearance to light colored hair) to reddened skin; small, raised skin lesions (known as “papular reactions”); dried discharge on the surface of the skin lesion (known as “crust”); hair loss (known as “alopecia”); darkened skin (known as “hyperpigmentation”); thinkening and hardening of the skin, usually associated with hyperpigmentation (known as “lichenification”); and excessively oily or dry scaling of the skin (known as “seborrhea”)
  • Inflammation of the moist tissues around the eye (known as “conjunctivitis”) may occur

Causes

  • Pollens(grasses, weeds, and trees)
  • Mold spores (indoor and outdoor)
  • Mallassezia a type of yeast found on the skin of animals
  • House-dust mites
  • Animal dander
  • Insects (controversial)

Risk Factors

  • Temperature environments with long allergy seasons and high pollen and mold-spore levels
  • Coexistent skin disorders characterized by itchiness (known as “pruritic dermatoses”), such as flea-bite hypersensitivity and adverse food reactions; these coexistent skin disorders increase the severity of the signs

Treatment

Health Care

  • Outpatient
  • Frequent bathing in cool water with shampoos designed to minimize itchiness can be beneficial

Activity

  • Avoid substances (allergens) to which the pet is allergic, when possible

Diet

  • Diets rich in essential fatty acids may be beneficial

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.

Immunotherapy (Hyposensitization or “Allergy Shots”)

  • Administration (usually subcutaneous [SC] injections) of gradually increasing doses of the causative allergens to the affected pet in an attempt to reduce their sensitivity to the particular substance(s)
  • Allergen selection–based on allergy test results, patient history, and knowledge of local plants that contribute pollen into the air
  • Indicated when it is desirable to avoid or reduce the amount of steroids required to control signs, when signs last longer than 4-6 months per year, or when nonsteroidal forms of therapy are ineffective
  • Successfully reduces itchiness (pruritus) in 60-80% of dogs and cats
  • Response to “allergy shots” is usually slow, often requiring 3-6 months and up to 1 year to see full effect

Cyclosporine

  • Cyclosporine (Atopica) is effective in controlling itchiness (pruritus) associated with long-term (crhonic) allergic skin disease (atopic dermatitis); many pets can be controlled adequately long-term with less frequent dosing (such as every 2-4 days), as directed by your pet’s veterinarian; frequent pet monitoring is recommended

Steroids

  • May be given for short-term relief and to break the “itch”-scratch cycle”
  • Should be tapered to the lowest dosage that adequatly controls itchiness (pruritus), as directed by your pet’s veterinarian
  • Prednisolone or methylprednisolone tablets
  • Cats may need methylprednisolone acetate treatment, administered by infrequent injection

Antihistamines

  • Less effective than steroids
  • Evidence of effectiveness is poor
  • Dogs–antihistamines include hydroxyzine, chlorpheniramine, diphenhydramine, and clemastine
  • Cats–chlorpheniramine; effectiveness estimated at 10-50%

Other Medications

  • Tricyclic antidepressants (TCAs, such as doxepin or amitriptyline) have been given to dogs to control itchiness, but their overall effectiveness and mode of action is unclear, not extensively studied in the cat
  • Topical triamcinolone spray 0.015% (Genesis, Virbac) can be applied to the skin over large body surfaces to control itchiness (pruritus) with minimal side effects

Follow-Up Care

Patient Monitoring

  • Examine pet every 2-8 weeks when a new course of treatment is started
  • Monitor itchiness (pruritus); self-trauma, such as scratching or licking; skin infection and possible adverse drug reactions
  • Once an acceptable level of control is achieved, examine pet every 3-12 months
  • A complete blood count (CBC), serum chemistry profile, and urinalysis–recommended every 3-12 months for pets on long-term (chronic)steroid or cyclosporine therapy

Preventions and Avoidance

  • If the substances (allergens) to which the pet is allergic to have been identified through allergy testing, the owner should undertake to reduce the pet’s exposure to these substances as much as possible; however, reduction of exposure seldom makes a significant improvement on the level of the pet’s itchiness
  • Minimizing other sources of itchiness ([pruritus], such as fleas, adverse food reactions, and secondary skin infections) may reduce the level of itchiness

Possible Complications

  • Secondary skin infection or inflammation of the skin due to yeast (Malassezia dermatitis)
  • Co-existent flea-bite allergy (hypersensitivity) and/or adverse food reaction

Expected Course and Prognosis

  • Not life-threatening, unless itchiness (pruritus) is not responsive to medical treatment and it is so disruptive that the result is euthanasia
  • If left untreated, the degree of itchiness (pruritus) worsens and the duration of signs lasts longer each year of the pet’s life
  • Some cases may resolve spontaneously

Key Points

  • Atopic dermatitis is a progressive skin condition
  • It rarely goes into remission and cannot be cured
    • Some form of therapy may be necessary to maintain quality of life

Nail & Nailbed Disorders

Nail & Nailbed Disorders – An Overview

  • Nail and nailbed disorders are a group of abnormalities or diseases that affect the nail or claw and/or the tissues surrounding the nail or claw (that is, the nailbed)
  • “Onycho-” or “onych-” refers to the nail or claw
  • Inflammation of soft tissue around the nail or claw (known as “paronychia”)
  • Fungal infection of the nail or claw (known as “onychomycosis”)
  • Brittle nails or claws that tend to split or break (known as “onychorrhexis”)
  • Sloughing of the nail or claw (known as “onychomadesis”)
  • Deformity of the nail or claw caused by abnormal growth (known as “nail dystrophy” or “onychodystrophy”) that is often the result of a nail or nailbed disorder
  • Softening of the nails (known as “onychomalacia”)

Genetics

  • Certain breeds appear to be more susceptible to nail and nailbed disorders than other breeds, suggesting a possible genetic basis

Signalment/Description of Pet

Species

  • Dogs
  • Cats

Breed Predilections

  • Brittle nails that tend to split or break (onychorrhexis)—dachshund
  • Symmetrical deformity of the nails or claws caused by abnormal growth (nail dystrophy or onychodystrophy) that is related to the autoimmune disease, lupus, or a lupus-like disease (condition known as “symmetrical lupoid onychodystrophy”)—German shepherd dog, rottweiler, possibly giant schnauzer and Doberman pinscher
  • Deformity of the nail or claw caused by abnormal growth (nail dystrophy or onychodystrophy) of unknown cause (condition known as “idiopathic onychodystrophy” [“idiopathic” means unknown])—Siberian husky, dachshund, Rhodesian ridgeback, rottweiler, cocker spaniel
  • Sloughing of the nail or claw of unknown cause (condition known as “idiopathic onychomadesis”)—German shepherd dog, whippet, English springer spaniel

Mean Age and Range

  • Symmetrical deformity of the nails or claws caused by abnormal growth (nail dystrophy or onychodystrophy) that is related to the autoimmune disease, lupus, or a lupus-like disease (symmetrical lupoid onychodystrophy)—3–8 years of age

Signs/Observed Changes in the Pet

  • Licking at the feet and/or nails
  • Lameness
  • Pain
  • Swelling, redness of the skin and tissues (known as “erythema”), and discharge from the nail or the area where the skin and nail or claw come together at the top of the toe (known as the “ungual fold” or “nail fold” or “claw fold”)
  • Deformity or sloughing of one or more nails or claws
  • Discoloration of the nail
  • Bleeding from the nail
  • Loss of one or more nails
  • Being “tender-footed”

Causes

  • Inflammation of soft tissue around the nail or claw (paronychia)
  • Infection or infectious disease—bacteria, fungus (known as “dermatophytosis”), yeast (Candida, Malassezia), demodectic mange mites (condition known as “demodicosis”), leishmaniasis
  • Immune-mediated disease—types include the following: pemphigus, bullous pemphigoid, systemic lupus erythematosus, drug eruption, symmetrical lupoid onychodystrophy
  • Tumor or cancer—types include the following: squamous cell carcinoma, melanoma, eccrine carcinoma, osteosarcoma, subungual keratoacanthoma, inverted squamous papilloma
  • Abnormal communication between an artery and a vein (known as an “arteriovenous fistula”)
  • Fungal infection of the nail or claw (onychomycosis)
  • Dogs—Trichophyton mentagrophytes (usually generalized fungal infection of the skin, involving the nails)
  • Cats—Microsporum canis
  • Brittle nails or claws that tend to split or break (onychorrhexis)
  • Unknown cause (so-called “idiopathic disease”)—especially in dachshunds; involves multiple nails
  • Trauma
  • Infection—fungal infection (dermatophytosis), leishmaniasis
  • Sloughing of the nail or claw (onychomadesis)
  • Infection
  • Immune-mediated disease—types include the following: pemphigus, bullous pemphigoid, systemic lupus erythematosus, drug eruption, symmetrical lupoid onychodystrophy
  • Decreased or inadequate blood flow (known as “vascular insufficiency”)—inflammation of the blood vessels (known as “vasculitis”); clumping together or agglutination of red-blood cells when the temperature of the cells drops below normal body temperature (known as “cold agglutinin disease”), such as exposure of the legs to cold weather
  • Tumor or cancer—types include the following: squamous cell carcinoma, melanoma, eccrine carcinoma, osteosarcoma, subungual keratoacanthoma, inverted squamous papilloma
  • Unknown cause (so-called “idiopathic disease”)
  • Deformity of the nail or claw caused by abnormal growth (nail dystrophy)
  • Condition caused by excessive levels of growth hormone, leading to enlargement of bone and soft-tissues in the body (known as “acromegaly”)
  • Increased levels of thyroid hormone in the cat (known as “feline hyperthyroidism”)
  • Zinc-responsive skin disorder (known as “zinc-responsive dermatosis”)
  • Congenital (present at birth) malformations of the nail or claw

Risk Factors

  • Inflammation of soft tissue around the nail or claw (paronychia) due to infectious causes—decreased ability to develop a normal immune response (known as “immunosuppression”), which may be related to immune-system problem of the body or to the use of medications to decrease the immune response; feline leukemia virus (FeLV) infection; trauma; and diabetes mellitus (sugar diabetes)
  • Sloughing of the nail or claw due to bacterial infection (bacterial onychomadesis)—excessively short nail trimming (into the quick) postulated to increase likelihood of bacterial infection and subsequent sloughing of the nail or claw

Treatment

Health Care

  • Inflammation of soft tissue around the nail or claw (paronychia)
  • Surgical removal of the hard part of the nail (known as the “nail plate” or “shell”)
  • Antimicrobial soaks
  • Identify underlying condition and treat specifically
  • Fungal infection of the nail or claw (onychomycosis)
  • Antifungal soaks—chlorhexidine, povidone iodine, lime sulfur
  • Surgical removal of the hard part of the nail (nail plate or shell)—may improve response to medication administered by mouth or injection (known as “systemic medication”)
  • Amputation of the third bone of the toe (known as the “third phalanx”), which is continued by the nail or claw
  • Brittle nails or claws that tend to split or break (onychorrhexis
  • Repair with fingernail glue (type used to attach false nails in humans), as performed or directed by your pet’s veterinarian
  • Remove splintered pieces
  • Amputation of the third bone of the toe (third phalanx), which is continued by the nail or claw
  • Treat underlying cause
  • Sloughing of the nail or claw (onychomadesis)
  • Antimicrobial soaks
  • Treat underlying cause
  • Deformity of the nail or claw caused by abnormal growth (nail dystrophy or onychodystrophy)
  • Treat underlying cause
  • Tumor or cancer
  • Determined by biologic behavior of specific tumor
  • Surgical removal of the tumor
  • Amputation of toe
  • Amputation of leg
  • Chemotherapy
  • Radiation therapy

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

  • Bacterial infection/inflammation of soft tissue around the nail or claw (paronychia)—antibiotics based on bacterial culture and sensitivity, administered by mouth or injection (systemic antibiotics)
  • Yeast (Candida or Malassezia) infection/inflammation of soft tissue around the nail or claw (yeast paronychia)—ketoconazole administered by mouth (systemic treatment); nystatin or miconazole applied to the affected area directly (topical treatment)
  • Fungal infection of the nail or claw (onychomycosis)—griseofulvin or ketoconazole administered by mouth (systemic treatment) for 6–12 months until negative fungal cultures; itraconazole administered by mouth for 3 weeks and then as directed by your pet’s veterinarian
  • Sloughing of the nail or claw (onychomadesis)—depends on cause; medication to decrease the immune response (known as “immunosuppressive therapy”) for immune-mediated diseases
  • Other medications include cyclosporine, tetracycline with niacinamide, pentoxifylline, vitamin E, essential fatty acid supplementations, and chemotherapeutic agents (such as azathioprine, chlorambucil)

Follow-Up Care

Patient Monitoring

  • Determined by underlying cause

Preventions and Avoidance

  • Determined by underlying cause

Possible Complications

  • Determined by underlying cause

Expected Course and Prognosis

  • Bacterial infection/inflammation of soft tissue around the nail or claw (paronychia) or fungal and yeast infection of the nail or claw (onychomycosis)—treatment may be prolonged and response may be influenced by underlying factors Fungal infection of the nail or claw (onychomycosis) and brittle nails or claws that tend to split or break (onychorrhexis)—may require amputation of the third bone of the toe (third phalanx), which is continued by the nail or claw, in order to get resolution
  • Deformity of the nail or claw caused by abnormal growth (nail dystrophy or onychodystrophy)—prognosis is good when underlying cause can be effectively treated
  • Sloughing of the nail or claw (onychomadesis)—prognosis determined by underlying cause; immune-mediated diseases and blood vessel/blood flow (vascular) problems carry a more guarded prognosis than do trauma or infectious causes
  • Tumor or cancer—removed surgically by amputation of the toe; some are highly malignant and may have already spread (known as “metastasis”) by the time of diagnosis

Key Points

  • Nail and nailbed disorders are a group of abnormalities or diseases that affect the nail or claw and/or the tissues surrounding the nail or claw (that is, the nailbed)