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Flea Allergy Dermatitis (FAD) in Cats

What is Flea allergy dermatitis?

Flea allergy dermatitis (flea bite hypersensitivity) is the most common skin allergy in cats. As the name suggests, it is caused by an allergic reaction to the saliva from a flea bite. There are 15 known allergens in flea saliva, each one is capable of causing an allergic reaction in the cat.

Just one bite from a flea is enough to trigger an allergic reaction in your cat.  Flea allergy dermatitis is one of the major causes of miliary dermatitis in cats.

What are the symptoms of flea allergy dermatitis in cats?

Symptoms vary depending on the degree of sensitivity. Common symptoms include:

  • Frequent scratching and biting of the fur, especially on the back and the base of their tail.
  • Raised bumps (papules) or scabs on the skin.
  • Thinning fur in the affected area.
  • Severe scratching can damage the skin and lead to secondary bacterial infection.


Treatment of Flea Allergy Dermatitis:

Your veterinarian will be able to diagnose flea allergy dermatitis. This can be done visually. Signs of fleas on your cat are a good indicator. However, extremely sensitive cats will have few if any fleas on them. This is due to excessive self grooming.   In such cases, to get a definite diagnosis that your cat is in fact allergic to flea bites and not something else then a intradermal skin testing is required. Treatment involves several areas:

  • Eliminating fleas from your cat and environment, and preventing re-infestation of fleas by regular flea treatment.

  • Treating secondary skin infections caused by excessive biting and scratching of the skin. This may involve a course of antibiotics, medicated shampoo and or a topical medication.

  • Antihistamines or steroid injections and or ointment may be prescribed by your veterinarian to control inflammation and reduce itching.

  • Anti-inflammatory injection to reduce the itching.

  • Hyposensitisation (desensitisation). This involves injecting minute amounts of flea antigen into the cat in the hope that it will re-programme the immune system so it's not hypersensitive to flea antigen.

  • Antibiotics to treat secondary bacterial infection, if present.

Prevention of Flea Allergy Dermatitis:

Strict flea control is the best way to avoid/limit your cat's exposure to fleas and therefore flea bite allergy.

Also see:

Cat fleas