Integrative Pet Vet column: What’s up with my cat’s rodent ulcer?
Integrative Pet Vet
Cats can have a variety of inflammatory skin problems. Some can result in ulcers in the lips or feet and nodular lesions in the skin. Rodent ulcer is an old term that has been replaced with indolent (or eosinophilic) ulcer. Today it is known to be part of a group of inflammatory skin disorders called the eosinophilic granuloma complex (EGC). Affected EGC areas may not bother the cat, or they can be very itchy as a result of certain cells (eosinophils) mistakenly releasing inflammatory substances into the tissues. Lesions can start as mild and progress to being ulcerated, discharge can be present, and can they can become infected. The progression can be accelerated and recovery complicated when the cat licks and chews at the inflamed areas. The trigger for the release of inflammatory substances is not always clearly defined but is thought to be part of a poorly regulated allergic reaction.
The EGC name was developed years ago to refer to a group of skin problems involving the eosinophil. The eosinophil is a white blood cell that is part of the immune system. It is involved with allergic reactions and defense against parasites like roundworms. Eosinophils circulate in the blood, but they also concentrate in the tissues, which is why they play an important role in EGC.
When activity of the eosinophils becomes excessive or poorly regulated, EGC can appear. These excessive or dysregulated eosinophilic activities have been associated with allergy reactions to food and/or environmental allergies, insect bite allergies (i.e. fleas and mosquito bites),or parasite, bacterial and viral infections. Since there are multiple possible allergens that trigger a reaction, identifying the offending allergen can sometimes be difficult.
There are three basic forms of EGC: 1) eosinophilic or indolent (rodent) ulcer, 2) eosinophilic plaque and 3) eosinophilic granuloma. Cats can have one or more of these forms at the same time. The eosinophilic granuloma form is the most common. It can be found anywhere on the body, including the tongue, palate, hind legs and foot pads. Affected areas on the legs can have raised, linear or nodular granuloma lesions. The eosinophilic plaque can also appear anywhere on the body but is most commonly seen on the abdomen. They can appear as red, angry hives. The eosinophilic ulcer is seen on the upper lips.
Diagnosis involves evaluation of the lesions, review of the medical history, and a thorough physical exam of the cat. This is important because there are other skin problems like bacterial and fungal infections, abscesses and skin or oral tumors that can look like EGC. Laboratory testing including specific blood tests and skin biopsy may be necessary.
Interestingly, EGC is seen more often in young cats (2-6 years of age) and is observed two-fold more frequently in females. There is speculation that there is a genetic predisposition in some cats. Fortunately, sometimes these lesions will spontaneously disappear. However, some will become progressively worse and require treatment. Typical treatment includes controlling bacterial infections if present, identifying the source of the allergen (and avoiding that allergen), and the use of glucocorticoids (steroids). In some situations, other immunosuppressive drugs may be needed. Food trials to identify food allergies may be helpful for management. In addition, efforts to identify the allergies to environmental allergens may be necessary. This may require keeping the cat indoors to limit exposure to common outdoor allergens or performing intradermal skin or serum testing. However, it is important to note that there are indoor allergens like dust mites that can trigger EGC. Skin parasites like fleas should be treated if present. EGC is a problem that can require lifelong support and management.
Integrative supportive approaches include evaluation of the intestinal biome (gut flora) for its potential role in immune modulation that may affect the cat’s ability to properly regulate the immune reaction to allergens. Providing probiotics for cats undergoing antibiotic therapy can be beneficial for management of the intestinal biome. While cats are relatively resistant to the side-effects of steroids, it can be helpful to provide support for the adrenal and liver during steroid therapy. Some cats respond to essential fatty acids found in fish oil. These steps can become important for cats with stubborn or difficult to mange EGC lesions.
If you have questions about EGC in your cat, contact your veterinarian.
Ron Carsten, DVM, PhD, CVA, CCRT was one of the first veterinarians in Colorado to use the integrative approach, has lectured widely to veterinarians, and has been a pioneer in the therapeutic use of food concentrates to manage clinical problems. He is also the founder of Colorado Animal Rescue (CARE). In addition to his Doctor of Veterinary Medicine, he holds a PhD in Cell and Molecular Biology and is a Certified Veterinary Acupuncturist and Certified Canine Rehabilitation Therapist. He practices integrative veterinary medicine in Glenwood Springs.
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