Ulcers on Your Cat ’s Lips and Tongue
(Eosinophilic Complex Disease)

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Ron Hines DVM PhD

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For the last thirty-five years a peculiar disease of house cats has confronted me. It goes by various names: Rodent Ulcer, Lick Ulcer, Eosinophilic Granuloma disease, Eosinophilic Complex. When I was nine years old, I saw it for the first time in my cat, Bubbles. Bubbles was an indoor-outdoor cat living in Chicago. The inner border of her left lip first became puffy. Then a small white, fibrous crater developed. It later appeared on the opposite lip and occasionally on the tongue. Sometimes it would spontaneously disappear. I looked it up in some veterinary textbooks. At that time it was called Rodent Ulcer and farmers believed that their cats got it from eating rats and mice.

As pathologists began to examine these lesions they noted that they were composed of inflammatory cells called eosinophils, neutrophils and scar tissue. No one has ever found a disease organism as its cause. In my experience, the lip form is the most common. A second form causes lightening-like lines of inflammation on the cats body skin while a third – more serious form affects various portions of the cat’s intestine causing vomiting ,diarrhea and weight loss. In a rarer form the cornea of the eye can be affected. I have never seen this disease in dogs or other animals – although I have read that it also affect horses. I moved about the World a bit. I saw this same disease in the Galilee and Jerusalem, the Cayman Islands, Texas and Florida. Long-hair and short-hair, fat and thin, purebred and mixed breed cats all seem equally affected.

So what causes Eosinophilic complex ?

No one knows. It has become evident to me that the problem is something that touches the cat or is ingested or inhaled by the cat. I know this because in all other diseases, eosinophils are associated with allergy. The other key clue I learned from an elderly veterinarian who took in a cat with this problem. It was a busy month and the cat was placed in a kennel and forgotten. A month later, when the veterinarian remembered why the cat was there, he was astounded to find that the problem had cured itself! This meant that whatever the cause was, the cause was absent at the animal hospital. I have noticed that the disease has been on the decline since powerful flea-fighting prescriptions such as Advantage have come on the market. I do not believe that diet is the sole cause of the problem since I have cured many cats of the oral form with simple cage rest at my animal hospitals. When this is ineffective or impractical, a 50-50 mixture of methylprednisolone acetate and procaine penicillin G injected into the lesion offers relief that can last up to a year. It should not be administered more than three times a year or diabetes may result. It has also been found that a drug called megesterol (Megace), which is used in human breast cancer as well as a birth control product; medroxyprogesterone acetate (Depo-Provera) will also cause this disease to go into remission. If low dose corticosteroids are used to suppress the condition drugs such as prednisolone or dexamethasone or triamcinolone given no more than three days per week should be used. A few cases respond to the administration of essential fatty acid supplements such as Derm Capsules. Cyclosporine was also reported to alleviate symptoms. Chlorambucil (Leukeran), an alkylating agent that alters DNA synthesis is also said to be helpful when combined with corticosteroids.

Surgical excision of these lesions is pointless. No laboratory tests are necessary to confirm a typical case of oral Eosinophilic ulcers. In the skin, intestinal and ocular form, an eosinophil count is usually elevated above 7%. I know of no new information on the cause or treatment of this perplexing condition that has appeared in the literature over the last fifteen years. I wish more studies would be run so that we could better help these pets.

An article in the January 05 issue of DVM magazine states that eosinophilic lip ulcers are the result of food allergies, flea allergies or feline inhalant allergies (Atopy). It also states that Felis domesticus allergen 1 (Felid 1) could be an autoallergen responsible for the lesions seen in this complex. When seen on the chin or footpads, eosinophilic granuloma complex has been associated with mosquito bites. When it forms on the inner sides of the rear legs it has been associated with fleas as well as genetic predisposition. When it occurs on the toe pads, cat litter has occasionally been implicated.

Recently, an organism call Bartonella has been implicated in chronic oral infections and eye lesions in cats. The diagnosis of Bartonella infection is made using a laboratory test called the Western Blot. When cats are positive for this organism it can be successfully treated using azithromycin, doxycycline or rifampin.

A 2012 article found that a course of amoxicillin/clavulanic acid seemed particularly effective in helping cats get over flare ups. You can read that article here.

If you and your veterinarians have had only limited success controlling this problem, consider switching you cat to a home cooked all-meat diet similar to one of these.