Q: I have spent a fortune on my 16-year-old former alley cat. My cat has scratched at his ear, at his cheek and under his chin to the point of causing bleeding. We have given the cat injections, steroids and antibiotics; we have treated the cat for ear mites; and he receives Revolution monthly, all without relief. We also have tried diet changes without improvement.
I hate seeing him scratch so frequently, to the point of losing all his fur under his chin. I live in a big city suburb, with many vets to choose from. We have tried four cat vets so far this. No one seems to have any answers.
A: Numerous things cause a cat’s itchy skin, with parasitic infestations, fungal infections, and hypersensitivities/allergies being some of the more common reasons. Flea infestation is a very common cause of itching in cats, but I’m sure that’s not the cause in your cat, because fleas are easy to diagnose and Revolution is an effective treatment.
Pediculosis (lice infestation) reportedly causes itching and hair loss in cats, although the condition is quite uncommon. Infestation with scabies mites is uncommon in cats, although it has been reported in a few cats with potentially immunosuppressive disorders, particularly feline immunodeficiency virus (FIV) infection. Signs of scabies infestation varies widely, with some cats barely showing any itchiness, while others showing intense itching. Finally, demodicosis (infestation with mites of the genus Demodex) can cause itching and hair loss, however, it too is relatively uncommon in cats. I have a feeling that parasites are not your cat’s problem.
Ringworm, a skin fungus, is the most common infectious skin disease in cats. It affects cats of any age, sex or breed; young cats, older cats and longhaired cats are more frequently affected. Ringworm is usually considered to be non-itchy. However, this varies widely, and one has to consider ringworm in the list of itch-inducing skin disorders in cats. This is diagnosed easily by doing a fungal culture.
Hypersensitivities/allergies are a common cause of itchy skin. Food allergy and atopy (allergy to airborne substances) are two common causes of allergy in cats. Food allergy can manifest in a variety of ways, but itching around the head, neck, ears and face is a classic pattern. Diagnosis is achieved by feeding a hypoallergenic diet – one that contains a protein source that your cat has never encountered, such as rabbit, venison, or duck – for 8 to 12 weeks. You said you tried cat diet changes. If you have not fed your cat a diet containing a novel protein source, or if you didn’t feed it for the entire 8 to 12 week period, you may want to give it another try.
Cat allergies to airborne substances (called “atopy”) such as pollens or dust can lead to itching. To truly diagnose atopy, consult with a veterinary dermatologist. The dermatologist will perform an intradermal skin test, injecting small amounts of allergens into the skin, and charting the skin reaction. A vaccine can then be produced that you inject into your cat to help control the allergy.
Cats with atopy usually respond dramatically to steroids, however, and you said that you have given your cat steroids, and that it hasn’t helped. I don’t know which steroid, what dose, and for how long you gave it, but if the proper dose was given and it had no effect, then atopy is probably not the cause. It’s time for you to consult a veterinary dermatologist. I’m sure there are board certified veterinary dermatologists who can examine your cat.
One final thought: Many cats develop hyperthyroidism as they get older. You didn’t mention in your letter if your cat has hyperthyroidism. If so, know that the drug used to treat this condition, methimazole (brand name Tapazole or Felizole), can cause intense itching around the head and face in a small percentage of cats to whom it is administered.