Feline miliary dermatitis has been known as 'scabby cat disease,' 'feline eczema,' and 'blotch.' The word 'miliary' is used because the lesions look somewhat like millet seeds. 'Feline' is the scientific word for cat and 'dermatitis' means 'skin inflammation.'
What causes feline miliary dermatitis?
Feline miliary dermatitis is not really a specific disease itself but a set of symptoms which can be caused by a vast number of diseases. The causes include:
- Allergies, e.g., food allergies, atopy - such as allergies to pollens, and flea allergies
- Bacterial infections
- Fungal infections
- Yeast infections
- Parasitic infections of the skin, e.g., mites, lice
- Hypersensitivity to intestinal parasites
- Autoimmune diseases
- Nutritional disorders e.g., biotin or fatty acid deficiencies
- Hormonal abnormalities
- Unknown causes
What are the signs of feline miliary dermatitis?
The lesions of feline miliary dermatitis are multiple small, crusty bumps with redness underneath. The lesions are sometimes limited to small areas of the body like the base of the tail (where the tail meets the body) or the head. In other cases, the lesions can cover a large portion of the body. Many times the lesions are itchy, sometimes severely so. In these cases, there may be more severe damage to the skin because of the constant scratching and licking by the cat.
How is feline miliary dermatitis diagnosed?
Usually the veterinarian can diagnose feline miliary dermatitis by simply examining the cat. The hard part is determining the cause of the problem. Sometimes, the location of the lesions is helpful. If the lesions are at the base of the tail, fleas are a common cause. If the lesions are around the head, there is a stronger possibility they could be caused by mites. The veterinarian will give the cat a complete physical and obtain a complete history from you. Your input is very important in attempting to find the cause of the problem.
The veterinarian will use a flea comb and careful examination to determine if the cat has fleas, the most common cause of miliary dermatitis. In addition to fleas, flea dirt (feces) may be found on the cat. The feces, or flea dirt will dissolve into a red color when moistened; this is because it is primarily digested blood.
The hair is examined for the presence of lice, and skin scrapings are performed to look for mites. (A skin scraping is performed by scratching the skin with a dull scalpel blade, placing the resulting material on a microscope slide, and examining it under a microscope.) Your veterinarian may also press some clear cellophane tape on the skin of the cat and examine that microscopically for mites.
Some hairs may be removed from the cat and cultured in the laboratory for ringworm (a fungus). It generally takes 10-14 days for the fungus to grow enough to identify it.
A fecal exam will be performed to determine if the cat has any intestinal parasites.
If a food allergy is suspected, the cat will be given a food trial. To perform a food trial, the cat is placed on a special food, generally only available through your veterinarian, for 2-3 months. If the condition improves, we put the cat back on her usual food. If she worsens, then we know it is the food that is causing the problem, and we put her back on a special diet that does not contain the problem ingredients. During the food trial, it is absolutely imperative that the cat receives no treats or other food.
If all of the above tests are normal, further testing and measuring the response to antibiotic and/or steroid treatment may be done to determine if the cat has an allergy or bacterial infection. An additional procedure that could be performed is a skin biopsy.
How is feline miliary dermatitis treated?
The treatment for feline miliary dermatitis depends on the cause. If the cat is on medication for other conditions, the medication will be stopped, if possible, to rule out the possibility of a drug reaction causing the dermatitis.
Fleas, lice, and some mites could be treated with a product containing pyrethrin. In addition, the environment should be treated as part of the flea control. Injections and special dips may be used for the other types of mites.
Ringworm would be treated with oral and topical medications containing a fungicide, and again the environment would need to be treated.
If intestinal parasites are found, the appropriate medication will be given.
If it is found that the cat is allergic to certain foods, the diet will be changed to eliminate those foods. The cat will need to be on that diet for the rest of her life.
If bacteria or yeast are causing the feline miliary dermatitis, antibiotics or antifungal medications would be given, and the cat may be bathed in special shampoos.
If the cat is scratching or the cause of the dermatitis is an autoimmune or allergy problem, steroids like prednisone are usually given. The cat may need to be on a high dose at first, and then it can be tapered down. Additional treatment for allergies can include antihistamines, fatty acid supplements as described below, and baths or sprays. Additional testing can be done to determine what the cat is allergic to and then 'desensitize' the cat with regular injections.
A fatty acid supplement is often recommended as part of the treatment. In addition, extra biotin may be added to the cat's diet.