Cat - Feline Eosinophilic Granulomas

What are feline eosinophilic granulomas?

Feline eosinophilic granulomas are peculiar lesions which may be found in cats affecting the skin and other sites. These lesions have a characteristic appearance when examined under the microscope with the presence of eosinophils which are a type of inflammatory cell - hence the name eosinophilic granulomas.

The most common site for these lesions is on the lips, usually the upper lips, where they appear as ulcers. They are sometimes referred to as 'rodent' or 'indolent' ulcers. The lesions can be small and hardly noticeable but can be quite extensive with a very obvious deficit of the lip. Occasionally bleeding occurs from the lesions. Although this is the most common site for eosinophilic granulomas they can also be found in other sites on the skin. At most other sites they appear as raised areas where the overlying fur is lost leading to a fleshy pink/yellow appearance to the lesion rather than as ulcers when the lips are affected. Common sites are the back legs and the belly. These skin lesions can be quite extensive and may be itchy for the cats, which may frequently lick and bite at the affected site. Eosinophilic granulomas can also develop in the mouth at a number of sites including the gums and palate.

What causes eosinophilic granuloma?

The cause of eosinophilic granulomas is not clear. They just seem to arise spontaneously. There is a suspicion that some form of allergic response may be involved especially in the recurrent cases of eosinophilic granuloma.

How can eosiniphilic granulomas be diagnosed?

Microscopic examination of a lesion is necessary to be absolutely certain of the diagnosis of eosinophilic granulomas. The appearance of the ulcers on the lips is generally very characteristic so your vet may not feel that a biopsy is required, particularly since this may accentuate the lip deficit. For lesions elsewhere on the skin or in the mouth your vet may advise that a biopsy is taken to confirm the diagnosis of eosinophilic granuloma and to rule out other possibilities. Biopsies can generally be obtained very simply but do require a general anaesthetic.

How is eosinophilic granuloma treated?

The most common method used to treat eosinophilic granulomas is to use corticosteroids. These can be given in a variety of different forms, but most often as tablets. In some cases the corticosteroids may be given by injection, occasionally directly into the lesion. There is usually a good response particularly with the most common form affecting the lips. Treatment is usually continued for some time (weeks to months) as eosinophilic granulomas frequently recur and prolonged treatment will minimise the chances of this happening. Potential side effects of using corticosteroids long term include increased thirst and appetite, lethargy, weight gain and development of diabetes. Any abnormal behaviour or signs noted should therefore be reported to your vet.

Some forms of eosinophilic granuloma prove more difficult to treat and in such cases your vet might decide to use additional treatments.

Since one of the potential causes of eosinophilic granulomas may be an allergy to fleas, good flea treatment is essential and this should be discussed with your vet. If your cat is attacking the lesions your vet may suggest fitting a special collar to prevent self-inflicted damage.

Some cats get eosinophilic granulomas as they are allergic to something in their diet, so your vet may suggest a particular 'prescription' diet as part of the treatment.

What is the outlook for eosinophilic granuloma?

Most cases respond very well to treatment. They do sometimes show a tendency to recur but this can usually be managed satisfactorily. Occasional cases do prove more difficult to treat but this is unusual.