Skin Allergy (Feline)

Allergies most often present as cat skin problems, whereas humans sneeze, cough and have a runny nose in response to allergens.

Cat skin allergies have many causes including sensitivity to inhaled particles, foods and insect bites.

Common name: Inhalant allergy, Food allergy, Flea bite allergy

Scientific name: Allergic Inhalant Dermatitis (Atopy), Food hypersensitivity, Flea bite hypersensitivity

Diagnosis

Signalment Any cat may develop an allergy resulting in skin problems. Most allergies develop in cats between the ages of one and three years. Cats that spend a significant amount of time outdoors are at increased risk of developing flea bite allergy or inhalant allergy since they are more likely to be exposed to fleas or environmental substances such as pollen and molds.

Incidence/prevalence Between 10 and 30 percent of cats will develop inhalant allergy. The incidence of food allergy in cats is unknown. Flea bite allergy is common in cats, and some veterinary dermatologists believe it to be the most common cat skin allergy.

Geographic distribution Inhalant and flea bite allergies are common in temperate climates and, during warmer months, in non-temperate areas. Food allergies have no geographical distribution.

Clinical signs (primary, most to least frequent, scientific term, synonyms) Itchiness (pruritis), Scratching, Licking, Chewing, Hair loss (alopecia), Red, irritated skin, Scaly areas, scabs or small bumps on skin.

Clinical signs (secondary, most to least frequent, scientific term, synonyms) Thickening and increased pigmentation of the skin, Vomiting hair balls or hair in the feces.

Cause (scientific, common term) Allergy or hypersensitivity to pollen or other environmental allergens, food or food additives or insect bites.

Organ system affected Skin, Gastrointestinal tract.

Diagnostic tests Intradermal allergy testing, Serum allergy tests, Hypoallergenic food trial.

Differential Diagnosis Cheyletiellosis, Otodectic mange (ear mites), Scabies, Dermatophytosis (ringworm), Psychogenic alopecia.

Overview

Cat skin allergies have many causes including inhaled environmental substances like pollen, mold, dust, dust mites and dander from other animals. Other causes are flea or other insect bites and foods or food additives.

Allergies most often present as cat skin problems, unlike in humans who sneeze, cough and have a runny nose in response to allergens. In many cases, a cat is sensitive to more than one of these allergens. Between 10 and 30 percent of cats will develop inhalant allergy. The incidence of food allergy in cats is unknown. Flea bite allergy is common in cats, and some veterinary dermatologists believe it to be the most common skin allergy in cats.

Affected cats are very itchy and will scratch, chew and lick excessively. They may have hair loss and their skin may be red and inflamed. The most typical presentation of cat skin allergy, called miliary dermatitis, includes small bumps on the skin along with scabs, crusts and inflammation. A veterinarian can develop a diagnostic and treatment plan for the affected cat.

Once the offending allergen or allergens are identified, avoidance of these substances is recommended. Additionally, medications may be required to control the clinical signs, or hyposensitization (allergy shots) may be recommended.

Treatment

Home Care Limit exposure to the identified allergen. If the cat is allergic to fleas, vigorous flea control on the cat and in the environment is necessary. A single flea bite will initiate intense itching. If the cat is allergic to pollen and molds, keep the cat inside to prevent allergens from accumulating on its coat. Bathing, if the cat will permit it, can also remove allergens from the fur. Some cats are allergic to house dust and dust mites. Air filters can be used in the home to decrease the concentration of these allergens. If a hypoallergenic food trial is recommended, no other foods can be given to the cat.

Professional Care A veterinarian will examine the cat and recommend a diagnostic and treatment plan. Allergy testing and a hypoallergenic food trial may be needed determine the cause of the allergy. The veterinarian may also prescribe medications to control the clinical signs, medications inclide glucocorticoids, antibiotics, antihistamines and fatty acid supplements. Hyposensitization or allergy shots may be recommended. Hyposensitization is accomplished by giving serial injections of increasing amounts of the allergens to increase tolerance.

Action Pet parents and their veterinarians will need to work together to control the cat skin problems. Often, avoidance of the allergens and treatment will need to be continued for the life of the cat.

Outcome Allergies to foods and insect bites can be managed effectively by changing to hypoallergenic foods or by keeping the cat and its environment free of parasites. Inhalant allergy is harder to control since it may be more difficult to avoid the allergens. However many atopic cats can be managed well by using medications to control the clinical signs or by hyposensitization.

Recommended Treatment See your veterinarian for proper care of suspected feline skin allergy.

References/Additional Readings

Scott, DW, Miller, WH & Griffin, CE. Skin Immune System and Allergic Skin Diseases. In: Muller & Kirk's Small Animal Dermatology, 6th Ed. Philadelphia: W.B. Saunders Company, 2001; 543- 642.

Hansen, BL & Schwartzman, RM. Immunologic Diseases. In: Melman, SA, ed. Skin Diseases of Dogs and Cats. Potomac: DermaPet Inc, 1994; 113-127.

Ackerman, LJ. Immune-Mediated Skin Diseases. In: Morgan, RV, ed. Handbook of Small Animal Practice, 3rd ed. Philadelphia: W.B. Saunders Company, 1997; 946-948.

Author

Camille DeClementi, VMD

DABT, DABVT

Editor

Steve Hansen, DVM, MS, MBA

DABT, DABVT