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Fleas Can Make Your Pet Very, Very Itchy


Pet Column for the week of June 16, 2003

Related information:

Services - Dermatology

Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
Ann Marie Falk
Information Specialist

Fleas are tiny wingless critters that annoy pets and disgust owners. Most pet owners will battle fleas or the allergic response fleas can cause. Flea allergy dermatitis-an inflammation and irritation of the skin-is the most common skin allergy in dogs and cats.

"Adult fleas are blood-sucking parasites that require a host, such as a dog or cat, for protection, food, and survival. When a flea bites an animal, a variety of irritating and/or allergy-causing substances from its saliva are injected into the skin," explains Dr. Adam Patterson, a veterinarian completing a residency in veterinary dermatology at the University of Illinois Veterinary Teaching Hospital in Urbana.

Although flea allergies may have a genetic component, there are no known breed, sex, or age predispositions. Animals with environmental allergies may be more likely to develop flea allergies, however. Dogs and cats generally develop this allergy between 2 and 4 years of age.

"Flea allergy is an extremely itchy condition that can be triggered by only a couple of flea bites. The abdomen and rump are the most commonly affected areas in the dog. These itchy areas may develop oozing scabs. Cats, on the other hand, typically overgroom; they may have hair loss but not develop skin lesions," says Dr. Patterson.

Fleas enjoy temperatures in the seventies and like 70 to 80 percent humidity. They do not do well at high altitudes. In most areas these restrictions make flea allergy a seasonal problem, rearing up in the spring and summer. Animals residing in southern states may have fleas and the resulting allergic reaction year round.

Diagnosis of a flea allergy is made based on pet's history, examination of the skin, presence of fleas, and response to treatment. Fleas may be seen crawling on the dog or cat. Fleas in hiding may be hard to spot, so veterinarians examine affected areas looking for flea excrement, also known as flea dirt, which looks like small, black to rust colored, comma-shaped dandruff. Unfortunately the absence of fleas or flea dirt does not rule out flea allergies.

To confirm that the particles found on a pet are flea dirt, place the substance on a wet paper towel. Flea dirt will turn a red or reddish-brown color signifying digested blood.

"Treatment for flea allergies requires flea control. In heavily infested areas, flea control treatment must include all in-contact pets and the pets indoor and outdoor environments. Skipping any of these areas may mean treatment won't be successful. If there's not a heavy infestation, treating the pet may be all that's necessary," says Dr. Patterson.

Flea preventatives are the simplest way to treat animals. If your pet has flea allergies, a topical adult flea preventative is better than an oral product. The goal is to kill adults before they bite so the animal is not exposed to saliva. Many products require monthly application.

Following the application instructions is critical to successful therapy. Your veterinarian may decide year round flea treatment is necessary. In addition, Dr. Patterson warns, "Products containing permethrin should not be used on cats. This chemical is toxic to cats."

Other therapy may be needed, depending on the severity of the allergic reaction. Antibiotics, steroids, and anti-histamines may be used to treat a secondary bacterial infection, helping to decrease the itching. Skin problems tend to clear up in 1 to 3 months after starting therapy. Treating flea allergies alone is not enough for a pet with multiple allergies. Your veterinarian will work with you to identify and treat the cause of your pet's discomfort.

"Flea allergies carry a good to excellent prognosis. Most pets live happy, itch-free lives after diagnosis and treatment. However, it must be remembered that this is an allergy that must be managed throughout the life of the pet. Altering or discontinuing recommended flea control can result in a miserable itchy pet!" says Dr. Patterson.

Getting rid of fleas will make both pet and owner happy. For more information on specific flea control products or with questions about diagnosing and treating flea allergies, contact your local veterinarian.