Cat - 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 be much 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 they may sometimes become infected. Cats may become very distracted by this problem and may seem to spend most of their time appearing to groom and attack 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 possible things. Other parasites such as cheyletiella (fur mites), harvest mites, lice and ear mites, can be responsible. It can occasionally represent an allergy to something in the cat's diet or a response to an inhaled allergen. Contact allergies are another possibility but are rare in cats - this could be an allergy to some synthetic material the cat comes into contact with or possibly some form of plant material the cat encounters outside.

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. Since a single flea bite can be responsible for quite severe skin problems, it is not always possible to find evidence of the fleas on examination of the cat, as the culprit may have 'visited' the cat only briefly and now left. In so many cases the suspicion of flea involvement is based more on circumstantial evidence of likely exposure to fleas. This may depend on contact with other cats and dogs. If you have other cats and dogs in your household your vet may ask to examine these for evidence of fleas.

Identification of causes of miliary dermatitis other than fleas can be difficult. This may involve collection of skin biopsies, scrapings or hair samples to check for other skin parasites. Diagnosis of allergies can be particularly difficult. Skin tests and trials with special diets aimed at minimising the risk of dietary allergies may be used.

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. See handout on Flea control. The key points in brief are that in addition to killing fleas on the affected cat, other cats and dogs in the household should be treated and measures are needed to try to kill any fleas that the cat is likely to be exposed to in the environment to avoid re-infestation. Since a single flea bite may be enough to induce the skin problem, the flea control needs to be rigorous. There are very effective flea treatments available now but the most effective treatments can only be obtained from a vet. They are also very convenient to use, with different types of drugs available as liquid that is spotted on the back of the neck, sprays, tablets and injections.