Home • Canine Health Articles • Inflamed Skin and Allergies
Inflamed Skin and Allergies
Inflamed Skin and 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
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
PET HEALTH LIBRARY
- The Pet Health Library contains information on some of the most common medical problems of dogs and cats. This information is designed to assist pet owners in better understanding their pets' health problems.
Cat Friendly Practice
- In the United States, there are millions more owned cats than owned dogs, yet cats visit veterinarians less frequently than dogs. A major reason is that it is very stressful to take cats to the veterinary practice and often owners believe their cat doesn't need routine check-ups for wellness and preventive care. The Cat Friendly Practice® (CFP) program, created by expert feline practitioners, provides a solution to this trend and provides an opportunity for veterinary practices to elevate care for cats and reduce the stress during the visit.