What Is Flea Allergy Dermatitis?

Flea allergy dermatitis is a skin condition that affects dogs with an allergy to flea bites. The skin of the host animal reacts negatively with a chemical deposited there while fleas are feeding on it. The animal shows an excessive tendency to scratch and may develop a small rash near the back, tail, and underbelly. Treatments for this condition involve protecting the animal from future flea infestations, thoroughly washing the coat and skin, and applying topical ointments. Veterinarians can administer more intensive therapy by injecting the animal periodically with cortisone.

This skin irritation is caused by a chemical naturally found in the saliva of fleas. Their saliva contains chemicals that are similar to histamine in structure, such as amino acids, phosphorus, and some aromatic compounds that can react with an animal's skin. The result is a rash and severe itching sensation. Flea allergy dermatitis is typically only diagnosed in pets between one and three years of age, and is almost never experienced by those younger than six months. The condition tends to lessen and dissipate with age.

Pet owners can look for certain common signs in their pet's behavior to determine if it has flea allergy dermatitis. Most pets who suffer from this allergy begin by scratching continuously. They tend to focus on the neck and behind the ears, as well as on the back just above the tail, and the joints where the legs and torso meet. The need to scratch can become so intense that many pets will pluck out their hair, creating what veterinarians refer to as a hot spot, revealing a bald patch of skin that is prone to scabs, sores, and infection when left untreated. Many pets will also exhibit a rash of small, red welts on the underbelly, the inner thighs, and near hot spots.

Treatment for flea allergy dermatitis can include medicated shampoo, anti-itch creams, oral medication, and cortisone injections. Any pet showing signs of this allergy should be treated with a flea deterrent, such as medicated drops, immediately. Specialty shampoos can be purchased that are formulated to neutralize skin reactions that result from insect activity, and do not negate the effectiveness of topical flea drops. Over the counter anti-itch and antibiotic creams can be applied for immediate relief to any skin areas the pet may have chewed bare of fur while scratching. Oral medications and cortisone injections should be discussed with and administered by a trained veterinarian.