When a flea bites your dog, it injects a small amount of saliva into the skin to prevent blood coagulation. Some animals may have fleas without showing discomfort, but an unfortunate number of dogs become sensitized to this saliva. In highly allergic animals, the bite of a single flea can cause severe itching and scratching. Fleas cause the most common skin disease of dogs – flea allergy dermatitis.
If your pet develops hypersensitivity to flea saliva, several changes may result:
- A small hive may develop at the site of the flea bite, which either heals or develops into a tiny red bump that eventually crusts over.
- The dog may scratch and chew at himself until the area is hairless, raw and weeping serum (“hot spots”).
This can cause hair loss, redness, scaling, bacterial infection and increased pigmentation of the skin.The distribution often involves the lower back, base of the tail, toward the back, the abdomen, flanks and neck. It may become quite generalized in severe cases, leading to total body involvement.Remember that the flea spends the majority of its life in the environment, not on your pet, so it may be difficult to find. In fact, your dog may continue to scratch without you ever seeing a flea on him. Check your dog carefully for fleas or for signs of flea excrement (also called flea dirt), which looks like coarsely ground pepper. When moistened, flea dirt turns a reddish brown because it contains blood.If one dog in the household has fleas, assume that all pets in the household have fleas. A single flea found on your pet means that there are probably hundreds of fleas, larva, pupa and eggs in your house.
If you see tapeworm segments in your dog’s stool, he may have had fleas at one time or may still have them. The flea can act as an intermediate host of the tapeworm, Dipylidium caninum. Through grooming or biting, the animal ingests an adult flea containing tapeworm eggs. Once released, the tapeworm grows to maturity in the small intestine. The cycle can take less than a month, so a key to tapeworm prevention is flea control.
The Life Cycle of the Flea
The flea’s life cycle has four stages: egg, larva, pupa and adult. The adult flea uses your dog as a place to take its blood meals and breed. Fleas either lay eggs directly on the dog where they may drop off or deposit eggs into the immediate surroundings (your home or backyard). Because the female may lay several hundred eggs during the course of its life, the number of fleas present intensifies the problem. The eggs hatch into larvae that live in carpeting, cracks or corners of the dog’s living area. The larvae survive by ingesting dried blood, animal dander and other organic matter. To complete the life cycle, larvae develop into pupae that hatch into adults. The immediate source of adult fleas within the house is the pupa, not the dog. The adult flea emerges from the pupa and then hops onto the host.
This development occurs more quickly in a warm, humid environment. Pupae can lie dormant for months, but under temperate conditions fleas complete their life cycle in about three weeks. The inside of your home may provide a warm environment to allow fleas to thrive year round.
Fighting the Flea
Types of commercial products available for flea control include flea collars, shampoos, sprays, powders and dips. Other, newer, products include oral and systemic spot-on insecticides.
In the past, topical insecticide sprays, powders and dips were the most popular. However, the effect was often temporary. Battling infestations requires attacking areas where the eggs, larvae, pupae and adults all congregate. Because some stages of a flea’s life can persist for months, chemicals with residual action are needed and should be repeated periodically. Sprays or foggers, which required leaving the house for several hours, have been used twice in 2-week intervals and then every two months during the flea season.
Treating animals and their living areas thoroughly and at the same time is vital; otherwise some fleas will survive and re-infect your pet.
As one might expect, flea control through these methods is very time consuming, expensive and difficult. The good news is that currently, with the newer flea products on the market, flea control is much safer, more effective and environmentally friendly. Current flea control efforts center on oral and topical systemic treatments. These products not only treat existing flea problems, they also are very useful for prevention. In fact, prevention is the most effective and easiest method of flea control.
One group of products works to control fleas by interrupting the development of fleas by killing flea larva and eggs. These drugs are called insect growth regulators (IGRs). These products do not kill adult fleas, but they dramatically decrease the flea population by arresting their development. One common oral product used is lufenuron (Program®). Lufenuron is given monthly, and is combined with heartworm protection in the product lufenuron/milbemycin Sentinel®. Lufenuron is also available as an injection that lasts 6 months. Methoprene and pyriproxifen (Nylar®) are also very effective IGRs that are available as sprays or collars.
Other products kill the actual flea (adulticides) and work quite rapidly. These include both spot-on and oral products. Spot-on products are usually applied on your pet’s skin between the shoulders. The medication is absorbed into the skin and distributed throughout the body. Fleas are killed rapidly on contact with the skin. Spot-on products include fipronil(Frontline®), Metaflumizone (ProMeris® and ProMeris Duo™), imidacloprid (Advantage®), and Selamectin (Revolution®). A recently developed oral adulticide is nitenpyram (Capstar®), that when given begins to kill fleas in 30 minutes. All these products are safer, easier to use and, if used correctly, the most effective method of flea control.
Additionally, some have the added benefit of efficacy against other parasites. Some veterinarians are even recommending a combination of an adulticide and insect growth regulator (Frontline Plus®) as a more complete method of flea control.With all these choices it is best to consult your veterinarian as to the best flea control and prevention for your pet. The choice of flea control should depend on your pet’s life-style and potential for exposure. Through faithful use of these systemic monthly flea products, the total flea burden on your pet and in the immediate environment can be dramatically reduced.
Keeping your pet on monthly flea treatments, especially in areas of high flea risk, is an excellent preventive method of flea control. These products often eliminate the need for routine home insecticidal use, especially in the long run. Although it may still be prudent in heavy flea environments to treat the premises initially, the advent of these newer systemic flea products has dramatically simplified, and made flea control safer and more effective.