Flea Allergy Dermatitis

Allergy to flea saliva is a common cause of itching in dogs and cats in Southern Califor­nia. The saliva injected into a sensitive animal from a single flea bite can cause itching for up to three weeks. An itch-scratch cycle of­ten develops, in which the itching causes the animal to scratch and chew, causing skin irritation, which leads to more itching and scratching.

 

The tendency to develop aller­gies is inherited. Often animals with flea allergy also have other allergies to inhaled sub­stances or food. These dis­eases cannot be cured, only controlled, and often become worse over time.

 

In dogs, flea allergy results in scratching and chewing, particu­larly along the back, tail, and thighs. This irritation can result in hair loss, redness, and bumps in these sensitive areas. Excessive chewing may result in a hair­less, red, oozing, painful area known as a "hot spot".

 

Cats with flea allergy will de­velop a scruffy appearance and often have bumps and scabs along the back, on the abdomen, and around the neck. Occasionally, cats will de­velop hair­less, firm, raised areas known as eosinophilic plaques.

 

Problems that commonly oc­cur secondary to flea allergy in­clude greasy, smelly skin (seborrhea oleosa); dry, flaky skin (seborrhea sicca); skin and ear infections; and eye irritation. Chronic irritation may re­sult in thick­ened, hairless, darkly pig­mented skin.

 

Flea control is the most im­por­tant treatment for flea allergic pets and must in­clude vigorous and regular treatment of all the animals, the yard, and the house. 

 

To relieve discom­fort, break the itch-scratch cycle and give time to implement the flea control pro­gram, the vet­erinarian may prescribe anti-inflammatory drugs (cortico­steroids). These medica­tions often cause increased ap­petite and water drinking. Cortico­steroids are strong drugs and can have side effects; therefore, it is important to follow the veterinarian's instruc­tions.

 

Fatty acid supplementation will help relieve itching and im­prove the coat in many animals. Fatty acids are often used with antihistamines or steroids to increase their effectiveness.

 

Topical medications can be an important part in the treatment of flea allergy dermatitis. Bathing in cool water with an oatmeal-based shampoo will help re­lieve itching. Antibiotics and antibacterial sham­poos may be pre­scribed for animals with skin infections. Antiseborrheic shampoos are used for pets with scaly, greasy, or waxy skin. A con­di­tioner or rinse will help with some conditions. Consult your vet­erinarian re­garding the correct shampoo to use for your pet's specific skin condi­tion. Treat­ment for hot spots include shaving and cleansing the area, and admin­is­tration of anti-inflammatory and antibiotic medications.

 

Some dogs with flea allergy der­matitis also have a condition known as hy­pothyroidism. Hypothyroidism may worsen the coat condition, cause excessive wax and scaling, contribute to skin infections, and lead to a “rat-tailed” appearance. For dogs with this disease, diagnosed by a blood test, supplementation with thyroid hormone pills may improve the coat and skin.

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