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Eosinophilic Granuloma Complex

Eosinophilic granuloma complex is the build-up of a type of white blood cell known as an eosinophil within the skin, resulting in nodules of inflammation called granulomas.

The underlying cause is thought to be a type of allergic reaction, where the cat’s immune system is over-reacting to an allergen in the environment.

Various allergens have been put forward as potential causes and include foods, flea bite saliva, inhaled allergens and certain fungal and viral infections.

Clinical Signs

There are three classic lesion types in this complex

-       Eosinophilic granulomas may be round or linear and can affect the chin, legs and paws. They are raised and red, and possibly ulcerated, but are not itchy

-       Eosinophilic plaques are hairless, raw sores within the skin and are mainly seen on the neck, back, thighs and armpits. They are commonly itchy

-       Indolent eosinophilic ulcers are pits or erosion, usually on the lips or inside the mouth. They are not usually painful or itchy.


The general appearance is often suggestive, but further testing is usually needed to confirm the diagnosis. The most reliable method is skin biopsy.


It is important to decrease the exposure to any suspected allergens.

Steroids are needed to resolve the lesions, and may be needed for several months before a response is seen. In some cases further immunosuppressive drugs are required.

If the underlying allergy can be found and controlled, response is usually satisfactory, and food and flea allergies are good examples of this.

Any cat with eosinophilic granuloma complex should receive regular effective flea control and a food trial should be implemented.

Unfortunately however, with so many potential allergies in the environment, it can sometimes be very hard, if not impossible, to determine the particular culprit. Also many allergens are impossible to remove from the environment.

As a result, some cats may have recurring episodes of this condition, and consequently will need repeated, or long-term medication.