Because flees like temperatures of 65-85 degrees fahrenheit, they are normally a summer problem for most climates. Dogs often get fleas from contact with other animals that already have fleas or just contact with the fleas themselves in their environment. The flea can jump a long way with its strong back legs, so the dog does not have to touch the fleas to get infested by them. The bite of the flea can cause a mild itch at best and a serious, health threatening condition at worst. If the dog is allergic or otherwise sensitive, this could make the situation worse.
To remove fleas there are four commonly used topically applied products that work. They are prescription based and can be acquired through a visit to the vet. They are Advantage, Frontline Plus, K9Advantix and Revolution. Each of these is unique, but kills the adult fleas present on the dog. With these topical applications, the fleas do not have the chance to bite the dog. This is a good choice for an allergic animal as the allergic reaction will not take effect. These prescriptions are normally to be applied once a month for up to three months for best effect.
There are products that control fleas that do not require a prescription to obtain and use. These will be less expensive normally and can be bought over the counter without a visit to the vet required. They may not be as effective in controlling the fleas however. Many will help against fleas, but may not work as well as other prescription products. These non-prescription products include shampoos, powders, sprays, mousses, dips and collars. These can be found in any pet store. Different brands or products will be more effective on certain dogs.