EOSINOPHILIC GRANULOMA COMPLEX

About the Diagnosis

Eosinophilic granuloma complex includes three distinct skin diseases in cats. All are thought to be a result of allergies or reactions to parasite infestations and respond to similar treatment. The name of the disorder comes from the observation that in all cases microscopic study of the affected tissues reveals large numbers of eosinophils. Eosinophils are a type of white blood cell that is involved in allergic reactions. Cats with one of the eosinophilic granuloma complex diseases may have allergies to fleas or insects, to food ingredients, or to environmental substances (pollen, house dust). Studies have shown that, at least in some cases, the tendency to develop these skin diseases is inherited genetically. This observation helps understand that eosinophilic granuloma diseases may flare up despite treatment and may persist for months or years.

• Eosinophilic plaques are hairless, flat, raised areas on the skin that are often red, moist, and glistening. Plaques are most often found in the groin or armpit or on the outside of the thigh. The condition seems to be very itchy, and cats will lick the areas constantly.

• Eosinophilic granulomas are hairless, raised, yellow areas; they often have sores on the surface. The most common site is along the back of the thigh, although other areas of the body can be affected. Eosinophilic granulomas can occur inside the mouth and on the tongue. Cats with mouth involvement may drool and be unable to eat.

• Indolent ulcer, or rodent ulcer, affects the upper lip. The lip becomes swollen, and a sore develops where the skin meets the mucous membrane of the inner lip.

Living with the Diagnosis

Skin problems caused by the eosinophilic granuloma complex tend to wax and wane. In some cats, the problem is seasonal. If the underlying allergic cause can be determined and controlled, the problem can be prevented from reoccurring. If fleas are present, a rigorous flea control program should be started. Seasonal problems may be due to bites of insects, such as mosquitoes, or to environmental substances that trigger allergic skin responses, such as inhaled pollens. Trials with restricted diets can be used for finding out if food allergies are involved. Restricted diets are specially formulated from a limited number of food sources to test for allergies to the common ingredients in commercial diets. Environmental allergies are determined by intradermal skin testing. Consulting a veterinary dermatologist may help in determining and eliminating underlying causes.

Treatment

All three forms of eosinophilic granuloma complex respond to treatment with corticosteroids (cortisone-like drugs). Administration may be either by mouth or by long-lasting injection. Long-term use of corticosteroids can have serious side effects, so an effort should be made to find the underlying cause of the allergic reaction and to eliminate it. If corticosteroids are used, they should be given for as short a period of time as possible. The skin problems tend to wax and wane, so reoccurrence is unpredictable except in cases that tend to reoccur seasonally. Since corticosteroids mask the problem, rather than eliminating it, an effort should be made to identify the cause and possibly use other types of treatment if effective. Here, too, a veterinary dermatologist may be extremely helpful.

DOs

• If giving medication by mouth, follow directions exactly.

• Realize the value of seeking a second opinion with a veterinary dermatologist for confirmation of the diagnosis and the most recent forms of treatment. Veterinary dermatologists are known as Diplomates of the American College of Veterinary Dermatology; your veterinarian can suggest a referral to one of these specialists.

DON'Ts

• Do not use lotions, ointments, or other topical medications on the areas unless directed to do so by your veterinarian. Cats quickly lick off topical medications, and some may be harmful if swallowed.

When to Call Your Veterinarian

• If the areas do not heal with the prescribed treatment.

• If the condition reoccurs.

• If your cat is having difficulty eating due to eosinophilic granulomas in the mouth.

Signs to Watch For

• See the description of each form of eosinophilic granuloma complex in the About the Diagnosis section.

Routine Follow-Up

• If your cat needs long-term corticosteroid treatment to control its skin disease, periodic testing may be recommended to watch for side effects