If you see a small black or dark brown insect moving on your dog's skin, you can safely assume your dog has fleas. If your dog has an infestation, you need to eradicate them.
Although there are more than 2,000 flea species in the world, the main culprit is the cat flea, Ctenocephalides felis. Fleas are amazingly adept, able to leap 8 inches at a time. They drink about 15 times their weight in their host's blood in a day. Female fleas can lay up to 2,000 eggs in their lifetime. They live about two to three months. The female flea lays the eggs on the animal, but they will fall off and hatch out in the carpet where the fleas' larvae and pupae eventually mature into adult fleas.
Flea Allergic Dermatitis
Fleas can cause flea allergic dermatitis and hot spots on dogs. Flea allergic dermatitis is an allergic reaction to flea saliva which causes the dog to have reddened skin, hot spots, scabs, itching, scratching and hair loss. This condition makes a dog feel miserable and may continue for a while even after the infestation has been dealt with.
Diseases Caused by Fleas
Fleas are much more than a nuisance. Huge infestations can cause anemia in dogs. What's more, the fleas can actually harbor some pretty scary diseases and parasites, like typhus and Rocky Mountain spotted fever. They can transmit bubonic plague and Bartonella, or cat scratch disease. Lastly, your dog can get tapeworms from fleas, should he accidentally swallow a flea while biting at it.
The best way to get rid of fleas is to consult with your veterinarian about what flea and tick products to use. Topical, spot-on flea control or monthly flea preventatives in pill form may be effective enough to get rid of fleas, but you'll need some way to get rid of them in your house. One way is to vacuum the floors, carpets and furniture thoroughly and throw out the vacuum bag in an outside trash can. You'll need to wash all sheets and bedding in hot, soapy water to kill any flea eggs, larvae or pupae that might be lurking there. You may need to use a special flea treatment in your house. Check with your veterinarian to make sure that it won't interact with the other flea treatments you're using and is safe for all the pets in your house. Some flea treatments are poisonous to cats, for example.