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, many 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 a hairless, raw and weeping serum (“hot spots”). This can cause hair loss, redness, scaling, bacterial infection and increased pigmentation of the skin.
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. Anemia also may be a complication of the flea infestation, especially in young kittens.