Flea Bite Hypersensitivity

FAD or Flea bite hypersensitivity is a hypersensitive reaction to the bite of the flea. When a flea bites a dog or cat (or human), it injects a small amount of saliva into the skin. It is this saliva that the patient develops an allergy to. Consequently, even one flea bite can cause intense itching and irritation. In turn, it can occur even when no fleas or flea dirt is found.  A severe flea infestation, where lots of fleas or flea dirt is found, can cause the same signs in non-allergic patients. FAD is most commonly seen in the summer months when fleas are more prevalent, but can occur even in Winter, because even low numbers of fleas can cause a reaction. Pets suffering from flea bite hypersensitivity will bite, chew and lick their skin continually.

Dogs typically attack their back, just above the tail, the back and insides of their hind legs, their belly and around the anus. This leads to scabs, hair loss, thickening and increased pigmentation of the skin and scaling, and eventually to weepy skin and sores.

Cats are affected slightly differently. Some cats develop small scabs over their back, or in severe cases over their whole body, which is called ‘miliary dermatitis’. Meanwhile, others lick until they develop bald patches especially on their belly and the back of their hind legs.

Conditions other than flea bites may cause similar signs, so we may recommend tests to confirm the diagnosis, especially when there is no evidence of fleas.

This condition is not life threatening but is not curable.  In the short term, hypersensitive pets who have been exposed to fleas and are suffering from FAD need medication to relieve the itching, stop them scratching and give their skin a chance to heal. Some will also need antibiotics for infections that have developed in the damaged skin.

In the long term, all pets suffering flea bite hypersensitivity need to have their exposure to fleas minimised - constantly.

There are many excellent products available to kill adult fleas, larvae and eggs both on your cat and in the environment. Easy to use spot-on applications include Revolution, Advantage, Advocate and Frontline. Where large environmental contamination with flea eggs exists, we usually recommend treatment with frontline spray.

Other pets in the household also need treatment constantly. Even though they are not affected (if they are not allergic), they do carry fleas which then can bite the allergic cat
Please talk with staff regarding a specific flea prevention treatment program for your cat.