Dealing with dermatologic problems in cats (and dogs) often requires a lot of patience. Picture this scenario: An owner brings in her cat with the complaint of itching and hair loss, and expects, not unreasonably, that a veterinarian will perform a physical examination, maybe run a few simple and inexpensive diagnostic tests, and come up with the answer to what the problem is and how to treat it. Unfortunately, that’s not always the way these scenarios play out.

The skin tends to respond to most insults in the same way regardless of whether they are parasitic, infectious, inflammatory, autoimmune, or allergic in origin. I searched a consultation site for veterinarians and entered "cat," "itching," and "hair loss" as my search parameters. The database came up with 109 diseases to consider. Yikes!

Knowing what’s wrong with a cat’s skin within minutes of starting a physical exam room is rare, which is one of the reasons why dealing with a condition that bucks this trend, like eosinophilic granuloma complex in cats, can be so satisfying.

The term "eosinophilic granuloma complex" refers to three types of lesions that look quite different but are actually very similar from a physiological point of view:

  1. An eosinophilic granuloma (also called a linear granuloma) typically develops as a long, narrow lesion running down the back of the thigh, or a lump on the lower lip or chin. Sometimes the footpads are involved. The skin is usually pink or tinged yellow, raised and bumpy, and hairless.
  2. Eosinophilic plagues typically affect the skin of the abdomen, inner thigh, throat, or around the anus. The areas are raised, pink or red, and appear "raw."
  3. Indolent ulcers (also called rodent ulcers) affect a cat’s upper lip and sometimes the tongue. These lesions usually look like pink, eroded sores.

In most cases, the clinical presentation of the three types of lesions that form the eosinophilic granuloma complex are distinctive enough that a physical exam is all that is needed to reach a diagnosis. Treatment is fairly straightforward as well. Most patients respond well to corticosteroids, although we sometimes need to hit the cats pretty hard with these drugs before we get the condition completely under control. Especially severe cases may necessitate the use of immunosuppressive drugs (e.g., cyclosporine or chlorambucil) or even surgery.

Wouldn’t it be nice if that were the end of the story? Finally, a feline disease that is easy to diagnose and treat. Unfortunately, that is only sometimes the case. It turns out that eosinophilic granuloma complex is usually a symptom of another, underlying condition — allergies. This may not be a big deal if your cat is allergic to flea bites, for instance. Put her on a good flea preventative and you shouldn’t have any more issues with eosinophilic granuloma complex. If however, your cat is allergic to something that is more ubiquitous, dust mites are a good example, eosinophilic granuloma complex can become a chronic problem that demands additional diagnostic testing (e.g., intradermal allergy testing or food trials) and long term treatment to prevent flare-ups.

Nothing’s ever simple, is it?

Dr. Jennifer Coates

Image: Happy new year cat by tanakawho / via Flickr