by Linda Bren

Fleas are truly devoted to their work. In one day, a single flea can bite your cat or dog more than 400 times. During that same day, the flea can consume more than its body weight of your pet's blood. And before it's through, a female flea can lay hundreds of eggs on your pet, ensuring that its work will be carried on by generations to come.

Fleabites may be merely a nuisance to some pets, but to others, they can be dangerous. They can cause flea allergy dermatitis--an allergic reaction to proteins in flea saliva. A pet's constant scratching to rid itself of fleas can cause permanent hair loss and other skin problems. A pet can get a tapeworm if it eats a flea that has one. And flea feasts on your pet's blood can lead to anemia and, in rare cases, death.

But fleas are not your pet's only nemesis. Tick bites can give your pet such infections as Lyme disease, ehrlichiosis, and Rocky Mountain spotted fever. And ticks can give those same infections to you. (For instructions on the safe removal of ticks, see "How to Remove a Tick.")

The good news is fleas and ticks are getting easier to control. "In the last five years, flea products have greatly improved," says Ann Stohlman, V.M.D., a veterinarian at the Food and Drug Administration's Center for Veterinary Medicine. Some flea prevention treatments also help kill ticks.

In years past, veterinarians recommended getting rid of fleas by simultaneously "bombing" the house with insecticide, spraying the yard, and dipping the dog or cat, says Stohlman. Today, treating only the pet often takes care of the problem. "But if there is a severe flea infestation or if the problem persists, you may still need to treat the pet's environment," she says.
Types of Flea and Tick Products

Hundreds of pesticides, repellents, and growth inhibitors are approved or licensed to control fleas and ticks on cats and dogs or in their environment. (See "Pet Products to Control Pests"). Products range from oral medications that require a veterinarian's prescription to collars, sprays, dips, shampoos, and powders that are available at retail stores. "Spot-ons," liquid products applied directly to the pet's skin, often behind the neck, are among the latest weapons to be developed to fight fleas and ticks. Some products kill only ticks or adult fleas--others break the flea life cycle by preventing flea eggs from developing into adult fleas.

Some flea and tick products are not prescription drugs, yet are available only through veterinarians. "This is because the manufacturer chooses to sell its products through vets, so that the vet can provide important safety information to the client," says Elizabeth Luddy, D.V.M., an FDA veterinarian.

The Preventic collar is one such product. The collar kills ticks by interfering with a tick's ability to feed on dogs. It contains the insecticide amitraz, which paralyzes the tick's mouthparts. Amitraz should not be used on dogs that are sickly, pregnant, or nursing, or with certain drugs that may interact with the insecticide. The manufacturer, Virbac Corp., Fort Worth, Texas, sells the collar through veterinarians, who can ensure that a dog is healthy and can use the collar safely.
When to Treat

It's best to treat your pet at the beginning of flea and tick season, says Stohlman. The severity and length of the flea season vary depending on which part of the country you live in. "It can last four months in some places, but in other places, like Florida, fleas can live all year long," says Stohlman. Fleas also can live inside a warm house year-round.

In many areas, September is often the worst month for flea infestation. In most parts of the United States, the greatest chance of infection by a tick bite is May through September, the period of greatest tick activity by "nymphs." Nymphs are the stage of tick development that occurs after they have had their first blood meal and molt, and before they become adults.
Lyme Disease

About 200 species of ticks live in the United States. Some of these can transmit infectious diseases, such as Lyme disease, to pets and humans. Studies indicate that dogs are 50 percent more susceptible to Lyme disease than humans, according to the American Veterinary Medical Association. Lyme disease is caused by a bacterium transmitted through the bite of the deer tick, also called the black-legged tick, which is no larger than the head of a pin.

Typical symptoms of Lyme disease in dogs include joint soreness and lameness, fever, and loss of appetite. Symptoms in humans include fatigue, chills and fever, headache, muscle and joint pain, swollen lymph nodes, and a red, circular skin rash.

Some of the products shown in "Pet Products to Control Pests" can control ticks on your pet. Many other tick repellents for pets and people are available in stores.