Miliary dermatitis (also known as miliary eczema, papulocrusting dermatitisor scabby cat disease) isn’t a specific disease but a disease complex. It is characterised by a red and crusty rash around the head, neck, and back, which is intensely itchy.
The two most common causes of miliary dermatitis are fleabite hypersensitivity and ringworm.
Flea bite hypersensitivity. up to 80% of cats with miliary dermatitis have flea bite hypersensitivity. Even if you don’t see any fleas or your cat is strictly indoors, it is still possible he has fleas. Just one flea is enough to cause an allergic reaction in a sensitive cat.
Allergies, inhalant (such as dust or pollen), food, contact, and insect (such as mosquitoes).
Ringworm a common fungal infection on the skin which causes circular lesions. There is a higher incidence of ringworm in Kittens and Persian cats.
Bacterial infections or overgrowth.
Yeast infections or overgrowth.
Mites including cheyletiellosis, ear mites, notoedric mange and demodicosis.
Red, crusty bumps and papules, especially around the head, ears, neck, and back (dorsal), often with intense itching.
As the head and neck areas are within reach of the claws, scratching can lead to self-trauma, resulting in large and often open scabs (known as excoriations).
Hair thinning or loss around the affected area.
Scratching, licking and biting the affected area.
Your veterinarian will perform a physical examination of your cat and obtain a medical history from you including if the miliary dermatitis is seasonal, if your cat has any concurrent diseases, what food he is eating and if he is on any medications or treatments, is the cat indoors/outdoors and does he receive regular flea treatment?
The location of the lesions may provide a clue as to the cause. If they are close to the base of the tail then fleas are usually the culprit. If they are around the head and ears, fleas, mites or food allergy may be the cause. In many cases, your veterinarian may recommend treating your cat for fleas, which is by far the most common cause of miliary dermatitis, to see if the problem resolves.
If there is no improvement he may decide to run the following tests:
Biochemical profile, complete blood count, and urinalysis are baseline tests to evaluate the overall health of your cat and look for underlying medical conditions.
Analysis of coat brushings, skin scrapings and fur samples to check for parasitic infections such as mites, fleas or fungal infections.
Skin prick test to see if inhalant antigens are the cause. An area of skin is shaved and a tiny amount of several common allergens are pricked onto the skin to see if there is a localised reaction.
A DTM (dermatophyte) culture for fungal infections. Hairs will be plucked from the affected area or a toothbrush will be used to collect samples which are then cultured on a special medium.
A fecal examination to detect the presence of intestinal parasites.
Blood serum IgE tests.
Skin scrapings are scrapings of several layers of skin which are then evaluated under a microscope to look for the presence of mites, fungal infections, and bacterial infection.
Skin culture involves taking a sample of skin and growing it in a culture to look for bacterial infection.
Food trials. If a food allergy is suspected, your cat will be placed on a food trial which involves giving him a novel source of food (such as kangaroo or lamb) for several weeks, excluding all other foods, including treats. If the miliary dermatitis improves, the cat will then be put back on his normal diet to see if the miliary dermatitis returns.
Treatment of feline miliary dermatitis depends on the cause of the problem.
Removal of the fleas from the cat and environment.
The same goes for mites, mange or fungal or yeast infections. Treat the cause and miliary dermatitis should go away.
Anti-parasitic medications to kill intestinal parasites.
Hypoallergenic diet for cats with food allergies.
Avoidance (where possible) if other non-food related allergies are the cause.
Antibiotics for secondary skin infections, if required.
In addition to the above treatments, fatty acids, shampoos, antihistamines, and corticosteroids to relieve itching and inflammation.