The symptoms of flea allergy can mimic other disorders of the skin. Before concluding that a dog is allergic to fleas, the examining veterinarian first will attempt to rule out allergies to food and inhalants, internal parasites, drug reactions, hair follicle inflammation (folliculitis), fungal infection, and other topical parasites -- all of which may have signs similar to an allergic reaction to fleas. A thorough history and physical exam will be required, during which the veterinarian will analyze the type and size of the skin lesions.
It is often very beneficial for dogs with suspected allergies to be tested for allergens that may be causing the dog to be itchy and uncomfortable. There are two common techniques that veterinarians can use to determine any underlying allergies to allergens such as fleas. One technique is called intradermal skin testing which requires the injection of different allergens into the skin. This usually is done by a veterinary dermatologist and may require sedation. The second technique involves taking a blood sample and sending it to a laboratory for allergy testing. This is called serologic allergy testing. There are varying opinions about serologic testing, so consultation with the examining veterinarian will be necessary.
