Feline Miliary Dermatitis/Flea Allergy Dermatitis

What is feline miliary dermatitis?

Feline miliary dermatitis is a general term to describe a skin condition that usually involves an allergic response. It is a very itchy skin problem and affected cats may lick, bite, and scratch at the affected skin. The cat’s response to the skin problem may lead to self-inflicted damage worsening the skin problem. The most commonly affected area is along the back and around the base of the tail, but it may become more extensive involving the neck, flanks and belly. The fur often becomes thin in affected areas and there may be angry looking red spots. These may scab over or sometimes become infected with bacteria. Cats may become very distracted by this problem and may spend a lot of time grooming or scratching the affected areas. 

What causes miliary dermatitis?

By far the most common cause of feline miliary dermatitis is allergy to flea bites. Some cats become particularly sensitive to flea bites and a single bite may be enough to provoke quite severe skin problems.

Miliary dermatitis can represent an allergy to many other things. Parasites other than fleas such as Cheyletiella (walking dandruff), harvest mites, lice, and ear mites can be responsible. It can occasionally represent a dietary or inhaled allergy. Contact allergies from bedding or outdoor plants are rare in cats but may also cause miliary dermatitis.

How is miliary dermatitis investigated?

The priority in investigation of miliary dermatitis is to rule out the possible involvement of fleas. Your vet may identify evidence of fleas on examining your cat’s coat. Their presence is more likely to be identified by recognising the presence of flea dirt rather than the fleas themselves as fleas spend little time on the cat and cats are effective in grooming them out of their fur, once they have been bitten. A single flea bite can be responsible for quite severe skin problems so you do not have to see an infestation of the coat before an allergy starts. If your cat has miliary dermatitis it is strongly recommended that you treat your cat effectively for fleas regardless of whether fleas are observed or not. Flea allergy is the most common allergy and potentially the most simple allergy to treat so it is important to eliminate this early in the investigation.

Identification of other causes of miliary dermatitis can be difficult. The first step usually involves skin scrapings or biopsies to check for other parasites. The diagnosis of food allergy involves a strict food trial for 8-10 weeks. Your veterinarian may suggest your cat sees a skin specialist (dermatologist) when the cause is not easily identified and particularly if your cat is suspected to have inhaled allergy (atopy) as the dermatologist can test your cat for this.

How is miliary dermatitis treated?

The key to successful treatment is identifying the underlying cause and dealing with this. Treatment will be directed initially at preventing fleas, even if no evidence of flea infestation is found. A separate handout is available giving information about flea control ("Flea Control in Cats"). For flea control it is important to treat all animals in the household and often the environment itself since a single flea bite may be enough to induce the skin problem, the flea control needs to be rigorous. There are very effective, safe and easy to administer flea treatments available; the most effective treatments usually obtained from a veterinarian.