Fleas in Dogs and Cats

The leading cause of skin problems in dogs and cats is the ordinary flea. Fleas can occur year-round in warm climates or on pets that live indoors. In colder climates, fleas are usually seen only in warm weather.

Adult female fleas survive by feeding on blood. The preferred host for this meal is your dog or cat, but in heavy infestations, fleas will readily bite humans. Most dogs and cats that are bitten by fleas will have some itching, but some pets develop a severe allergic skin condition called flea allergy dermatitis.

Heavy flea infestations can even cause anemia and death. And fleas carry dog and cat tapeworms. Your pet gets tapeworm infections from biting infected fleas.

Fleas can be diagnosed on your pet by finding the adult fleas, the flea dirt, or flea eggs on the skin. These can be seen most easily on the rump and the thinly-haired belly. Flea dirt is actually flea feces from digested blood. It looks black, but will appear red brown when smeared on a white paper. Flea eggs look like tiny, white sand grains. Adult fleas are small, brown and wingless, a little larger than the size of a pinhead. They move fast and can leap great distances.

To effectively eliminate fleas from your pet and your environment, you must disrupt the life cycle of the flea. The adult fleas you see represent only one percent of the flea population. The other 99 percent are the mostly unseen eggs and immature developing fleas that live in your rugs, furniture, the pet's bedding, or outside. To control fleas, you must control this reservoir of developing fleas as well as the adults.

The best products currently available from your veterinarian include flea shampoos, dips, sprays, powders and flea combos to control the adult fleas on your pets, and newer products that can be used on your dogs and cats monthly to control both adult and immature fleas. Be sure to treat all the animals in your household. Untreated pets are a reservoir for more flea production. If you have a heavy infestation, you may need to treat your house and yard with products specifically designed for use on rugs, furniture, pet bedding or lawns. Your veterinarian can tell you which products will be safest and most effective for your situation.

OSU Factsheet


Content provided by Iowa State University College of Veterinary Medicine for educational purposes only.

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