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Eosinophilic Granuloma In Cats

rodent ulcer

Eosinophilic granuloma complex (EGC) is a condition characterised by the presence of skin lesions over various parts of your cat's body. The cause isn't entirely known, but it is believed it may be a reaction to certain allergens such as flea bites, food or inhalant allergies.

An eosinophil is a type of white blood cell which participates in allergic reactions and helps to fight certain parasitic infections. A granuloma is an inflammatory lesion which contains granulocytes, which are a type of white blood cell which is made up of small cytotoxic granules, which are released (known as degranulation) in response to a microorganism or parasite.

The eosinophil's job is to attack parasites. It is attracted to areas where parasites occur and once there, it will release its granules to destroy the parasite. In cats with eosinophilic granuloma complex, eosinophils are called to the site of an allergic response and the biochemicals cause damage to the local collagen resulting in the granulomas commonly seen in this condition.

There are no breed, sex or age predispositions, although eosinophilic granulomas are  more often seen in cats under two years of age.

What are the symptoms of eosinophilic granular complex?

Some cats may only experience a single episode, while others may have multiple outbreaks. There are three different lesions found in eosinophilic granuloma complex:

  • Indolent ulcer (also known as an eosinophilic ulcer or rodent ulcer): This affects cats of all breeds and ages, although is seen three times as often in females as it is in males. Lesions most often occur on the upper lip (around the middle area), but can also be observed on the tongue. They appear as a raised, thickened red/brown ulcer which is well defined and glistening. Generally, while they may look so, they are not painful to the cat.
  • Eosinophilic plaque: Once again, this is seen in cats of any breed or sex. The lesion can appear on any part of the body, but most often are seen on the abdomen or thighs. They appear as red, well-defined, raised, hairless lesions which may be ulcerated.
  • Eosinophilic granuloma (also known as linear granuloma or collagenolytic granuloma):  This is more commonly seen in males than females, and teenaged cats (under 2 years of age) are most often affected. Commonly seen on the back legs lesions (although they can appear anywhere, appear as long, straight, thin lines which are raised and inflamed, and pinkish-yellowish in colour. Distribution on the face is seen as swellings and nodules on the bottom lip and the cat has a "fat chinned" pout. Footpads may also be affected by eosinophilic granuloma.

How is eosinophilic granuloma complex diagnosed?

Your veterinarian will perform a physical examination of your cat, paying careful attention to the lesions. He will obtain a medical history from you including how long lesions have been present, other symptoms you may have noticed and any known allergies.

He may wish to run tests to rule out other conditions such as fungal cultures to rule out ringworm and bacterial cultures to check for skin infections.

A tentative diagnosis may be made by visual examination of the ulcers. Your veterinarian may also decide to take biopsies of lesions for examination under a microscope.

Food trials and skin prick tests may also be recommended to determine if your cat suffers from food or other allergies. A skin prick test is a test where multiple common "allergens" are pricked onto your cat's skin, which is then evaluated 1-2 days later, if any of the pricks are raised and reddened, it can be indicative of an allergy to one (or more) of the allergens he was exposed to during the test.

How is eosinophilic granuloma complex treated?

If it is at all possible, identify the underlying cause and treat accordingly. This may include:

  • Ensuring the cat is parasite free. Regularly, treating for fleas and worms.
  • Avoiding and or eliminating suspected allergens.
  • If the cause is believed to be caused by flea bite hypersensitivity, food allergies or inhalant allergies flea control, hypersensitization or feeding a hypoallergenic diet may be recommended.

In addition to addressing the underlying causes outlined above, treatment of the lesions may include:

  • Steroids to reduce inflammation.
  • In severe cases, your veterinarian may prescribe immunosuppressive drugs such as Interferon.
  • If lesions are unresponsive, surgical excision or antibiotics may be tried.

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Image courtesy of Rocky Mountain Feline Rescue