With nearly 2,000 species and subspecies, fleas thrive in warm, humid environments, and feed on the blood of their hosts. Dogs play host to the cat flea (Ctenocephalides felis), whose dark brown or black body is usually one to three millimeters in length.

Why Are Dogs Susceptible to Fleas?

Fleas are hearty and nimble, and when searching for a host, they can jump 10,000 times in a row (the length of three football fields). Three pairs of legs make for excellent leaping capabilities (up to two feet), and a laterally flattened body allows for quick movement in a dog’s fur.

With a complete life cycle ranging anywhere from 16 days to 21 months, depending on environmental conditions, fleas are most commonly found on a dog’s abdomen, the base of the tail and the head. With heavy infestations, however, fleas can thrive anywhere on the body. They feed once every day or two, and generally remain on their host during the interim.

What Are Some Signs of Fleas in Dogs?

• Droppings or “flea dirt” in a dog’s coat
• Flea eggs on dog or in dog’s environment
• Allergic dermatitis
• Excessive scratching, licking or biting at skin
• Hair loss
• Scabs and hot spots
• Pale gums
• Tapeworms

What Are Some Complications of Fleas in Dogs?

Since fleas can consume 15 times their own body weight in blood, they can cause anemia or a significant amount of blood loss over time. This is especially problematic in young puppies, where an inadequate number of red blood cells can be life-threatening to some dogs. Signs of parasitic anemia include pale gums, cold body temperature and listlessness.

When a dog has a heightened sensitivity to the saliva of fleas, just one bite of a flea can cause an allergic reaction. This condition is known as flea allergy dermatitis and causes intense itching and discomfort for your dog. Signs include generalized hair loss, reddened skin, scabs and hot spots. Flea allergy dermatitis often leads to skin infections.

Are Certain Dogs Prone to Fleas?

Dogs who live in warm, humid climates, where fleas thrive at temperatures of 65 to 80 degrees, and those who live outdoors are most vulnerable to fleas.

What Should I Do If I Think My Dog Has Fleas?

Consult your veterinarian, who will confirm the diagnosis and discuss appropriate treatment options. It is important to tailor your treatment to your pet and his environment, since certain products in combination can be toxic. Your veterinarian can also determine the best plan for preventing fleas in the future.

How Do I Treat Fleas?

• It is important that all of your pets are treated for fleas, including indoor and outdoor cats, and that the environment is treated as well.
• Speak with your veterinarian about choosing the right flea treatment product. Common options include a topical, liquid treatment applied to the back of the neck, shampoos, sprays and powders. Some products kill both adult fleas and their eggs, but they can vary in efficacy. It is very important not to use products on your dog that are intended for cats (and vice versa). Prescription products are generally more effective and safer than over-the-counter products.
• Thoroughly clean your house, including rugs, bedding and upholstery. (Remember to discard any vacuum bags.) In severe cases, you might consider using a spray or fogger, which requires temporary evacuation of the home.

How Can I Prevent Fleas?

Using a flea comb on your dog and washing his bedding once a week will go a long way toward controlling flea infestation. Also, it is important to treat your yard as thoroughly as your house. Concentrate on shady areas, where fleas live, and use an insecticide or nematodes, microscopic worms that kill flea larvae.