Flea Bite Allergy
We have three dogs and a cat who spend most of the time in the house, but are outdoors some of the time, especially when the weather is nice. One of the dogs recently developed a rash on the top of her tail, near her rump. She has chewed the area until the skin is infected and the hair is thin. The veterinarian said she has flea bite allergy. We saw only two fleas. The other animals seem to be fine -- no fleas or skin problems. What causes the allergy and why aren’t the other pets affected? Also, how do we get rid of a flea problem?
Flea bite allergy is very common in both dogs and cats. Not all animals are allergic to flea bites, but the problem can be severe in pets that are allergic.
Fleas thrive well in warm, humid environments, so late summer typically is the peak of flea season. When a flea bites an animal, it injects saliva to prevent the blood from clotting at the feeding site. The allergy is due to sensitivity to this saliva and causes a pruritic or itchy rash in an area near the bite. The affected area might be quite large and may become infected and extremely painful, especially if the animal scratches or chews at it. This is often called a “hot spot”, and requires the attention of a veterinarian. Areas typically affected include the tail head, dorsal rump, back of the rear legs and sometimes the belly.
A single flea bite may be sufficient to trigger a reaction in allergic patients. Sometimes few, if any, fleas are actually seen on the animal. We usually identify the allergy by observing the fleas, flea dirt (excrement), and eggs along with the skin reaction. The diagnosis can be confirmed with an intradermal skin test and/or serology or blood test.
If one animal in a household with multiple pets has fleas and comes into the house, it is safe to assume that all the pets have fleas and that the house is infested. Fortunately, there are several excellent products available for treatment and prevention of fleas for both pets and the house. The staff at your veterinarian’s office can help you work out a plan that suits your need