When the dog is bitten, flea saliva is deposited in the skin. Just one bite causes intense itching. This type of reaction is not to the flea itself but rather to proteins in its saliva. Dogs most prone to this problem, interestingly enough, are not dogs who are constantly flea ridden, but those who are exposed only occasionally! A single bite can cause a reaction for five to seven days, so you don't need a lot of fleas to have a miserable dog.

The dog's response to the intense itching is to chew, lick, or scratch. This causes hair loss and can lead to open sores or scabs on the skin, allowing a secondary bacterial or yeast infection to begin. The area most commonly involved is over the rump (just in front of the tail), and left untreated will very often develop a yeast infection. Many flea allergic dogs also chew or lick the hair off of their legs, leading to hot spots.

In most parts of the country, the problem is seasonal. It is most severe in summer and fall in areas of the country that have cold winters. In warm climates where fleas are active year-round, they are a year-round problem, intensifying during summer.

Veterinarians may recommend treatment with small amounts of corticosteroids to give some affected pets relief during the flea season. However, these treatments may be dangerous to your pet if prolonged and only offer relief of symptoms at best.

The most important treatment for flea allergy is to get the pet away from all fleas. Therefore, strict flea control is the backbone of successful treatment. Unfortunately, complete flea control is not always possible for pets that live outdoors in warm and humid climates, where a new population of fleas can hatch out every 14-21 days.