Flea Allergy Dermatitis in dogs

This is the most common allergy in dogs. It is caused by a hypersensitivity reaction to one or more substances in the saliva of fleas. Flea allergy dermatitis is an allergic reaction of both the immediate and delayed type; itching begins immediately and tends to persist long after fleas have been eliminated. One bite is enough to trigger this reaction. Symptoms are worse in midsummer during the flea season. However, dogs who live in the house may suffer all year long if fleas are present.

Flea allergy dermatitis is characterized by severe itching with inflamed skin and red papules found where fleas are heavily concentrated—over the rump and base of the tail, under the legs, and on the groin and belly. Dogs chew and rub at these areas. Hair falls out and the skin becomes dry and scaly. In some cases the skin breaks down and develops raw areas that become crusted and infected. In time, the skin becomes thick and darkly pigmented.

The diagnosis can be suspected by finding fleas on the dog and seeing the characteristic skin rash. Check for fleas by standing your dog over a sheet of white paper and brushing the coat. White and black grains of sandy material that drop onto the paper are flea eggs and feces. An allergic response to flea saliva can be confirmed with an intradermal skin test.

Treatment: The majority of dogs with flea allergy dermatitis can be cured by eliminating fleas on the dog and controlling fleas in the environment. All pets in the household, even those who are not affected, must be treated simul- taneously to eliminate fleas. Antihistamines and/or corticosteroids may be required for two to three days to control itching. A medicated bath may also help to make your dog more comfortable. Pyoderma requires topical and oral antibiotics. Seek veterinary attention for these problems.

Prevention: The monthly application of a flea-control product, such as Frontline Plus or Advantage, will kill adult fleas before they bite the dog. Program inhibits reinfestation by preventing fleas from reproducing. The combination of Program with Frontline or Advantage should eventually eliminate fleas, but for a more rapid response it may be necessary to treat the environment as described in Eliminating Fleas on the Premises.