Flea Control in Dogs

How can my dog get fleas?

Fleas can spread directly from a flea-infested animal to your dog, but usually dogs get fleas from their environment.

Fleas live, feed, and mate on many animals, including cats, dogs, rabbits, ferrets, opossums, rodents, and racoons. Flea eggs fall off these animals, into the environment, where they hatch into larvae. The larvae eat organic debris until they mature into pupae. The pupae may lie dormant for weeks to months, awaiting the ideal environmental conditions before hatching into adults. 

Newly hatched adult fleas jump onto a host animal to complete their life cycle. Two days after eating a blood meal from the host, the female flea begins to lay eggs, which then drop off into the environment, and the cycle starts again, spreading fleas to more animals. Under ideal conditions, the flea can complete its entire life cycle in as little as two weeks; in adverse conditions, the cycle can take as much as a year.

Homes with carpets and central heating provide ideal conditions for the year-round gof fleas. The highest numbers of flea eggs, larvae, and pupae are found in areas of the house where pets spend the most time, such as their beds and furniture.

"Homes with carpets and central heating provide ideal conditions for the year-round growth of fleas."

Even if fleas are in your house, you probably will not see them. The eggs are tiny, white specks the size of dust particles, while the larvae are somewhat larger, with dark heads and lighter bodies. They migrate deep down in carpets, furniture, or cracks in floors away from the light.

Are fleas harmful to my dog?

Fleas can cause anemia (low red blood cell count) in heavy infestations, especially in young or debilitated dogs. A single female flea can consume up to 15 times her body weight in blood over the several weeks of her adult life. In addition, fleas can carry several diseases, including plague, and they act as hosts for one of the most common tapeworms in dogs and cats (see “Tapeworm Infection in Dogs” for more information).

How do I treat my dog if he has fleas?

Shampoos, sprays, powders, topical, and oral preparations are available. There are very effective products designed to be administered once per month or once every three months. Some of these products are conveniently combined with medications to prevent heartworm and intestinal worms. Some products contain adulticide ingredients (kills adult fleas) that remain active between scheduled doses, while others contain insect growth regulators (IGRs) that prevent the larval stages from maturing. For best results in a flea infestation, use flea control products that contain an IGR. Newer products have the combined advantages of adulticides and IGRs and are available through your veterinarian.

ALWAYS READ THE LABEL CAREFULLY - apply the product as instructed and repeat at the intervals stated. Some flea control drugs for use in dogs are poisonous to cats. Be sure to consult your veterinarian to choose the most effective and safe flea control products for your home and pet(s).

How do I treat the environment?

A number of products are available to kill the adult and larval stages of fleas and stop the flea life cycle, such as:

• adulticide sprays for use in the house
• sprays containing IGRs for use in the house
• insecticides applied by professional pest control companies

Sprays should be used in places where the flea eggs, larvae, and pupae are likely to be. Treat the entire household first and then concentrate on the hot spots - your dog’s favorite napping spots, such as soft furniture, beds, and carpets. Once they hatch from the egg, flea larvae move away from the light and burrow deep into carpets and into other nooks and crannies where they are difficult to reach. Be sure to move cushions, furniture, and beds to spray underneath them. Other places larvae are likely to live include baseboards and the cracks and crevices between floor seams or floorboards.

Flea eggs and pupae are very tough and resistant to insecticides. To remove eggs, as well as dead fleas, your pet's bedding should be washed in hot water or replaced. Regular and thorough vacuuming of your carpets, floors, and soft furnishings can remove a large number of flea eggs, larvae, and pupae. You will need to throw away the vacuum bag to prevent eggs and larvae from developing inside the vacuum cleaner. Vacuuming prior to the application of a spray is helpful because the vibrations will encourage newly developed fleas to emerge from pupae, which will then be killed by the insecticide.

What about the outdoor areas where my dog spends a lot of time?

Concentrate on dark, shaded areas and the areas where he sleeps, including his bedding. Spray a product containing an IGR and repeat every 14-21 days for three to five applications. Using a flea preventive recommended by your veterinarian is also very important to keep fleas away from your dog while he is outside.

Are insecticides safe for my dog and my family?

Insecticides for flea control should be safe both for pet dogs, cats, and humans, as long as the manufacturer's instructions are carefully followed. Avoid combining insecticides with similar modes of action. Always seek your veterinarian's advice if you are unsure and always tell your veterinarian about any flea control products you may be using other than those that have been prescribed. When properly used, side effects are quite rare and do not affect all dogs.

"Insecticides for flea control should be safe both for pet dogs, cats, and humans, as long as the manufacturer's instructions are carefully followed."

Certain types of pets (e.g., birds, fish, amphibians, reptiles, and invertebrates) may be susceptible to some products. Consult your veterinarian for advice before using flea control products in the rooms where these pets are kept.

I noticed my dog had fleas after his return from boarding. Did he get fleas there?

Not necessarily! Pre-adult fleas can survive for up to 140 days within their protective pupa. When you or your pets are absent from home for extended periods of time, these adult fleas remain in the pupae because no host is available. As soon as you or your pet returns home, these fleas emerge in large numbers and jump onto cats, dogs, and even people in the search for a blood meal. Vibrations (from walking) and/or increased carbon dioxide (from breathing) triggers the fleas to emerge from their pupae.

Why does my dog still have fleas after treating him and the environment?

The apparent failure of treatment is almost always the result of improper application of the preventive, inadequate treatment of the home, or exposure to other infested pets or environments. There is no evidence of fleas developing resistance to insecticides, especially topical flea preventives that contain a sterilizing agent or IGR in addition to the adulticide. Most of these problems can be overcome by using a veterinarian-recommended flea preventive product on your dog in addition to treating your home.