Dog Allergy Blood Test

A blood test can check for allergies in dogs.

It's common for dogs to have allergies. A dog can be allergic to food, pollen, mold, ingredients commonly found in shampoos and flea bites, among other things. When a dog inhales or ingests an allergen he may itch and scratch, his nose may run and he may develop redness and swelling in a specific area on his body. A blood test is a common method for detecting allergies in dogs.

Purpose

A blood test can identify antigen-induced antibodies in the dog's blood. These essentially cause a reaction in the dog when he's exposed to an allergen. The test results help veterinarians prepare a treatment plan.

Testing

Pet Education recommends performing blood tests when the dog's allergies are at their worst to ensure a more accurate result. In addition, it suggests placing the dog on a homemade, hypoallergenic diet---one high in protein and carbohydrates---prior to administering the test. The diet helps to eliminate possible food allergies affecting the dog, so atopic allergies caused by environmental irritants can easily be identified. A complete exam of the pet is required to rule out symptoms related to other skin conditions or fleas.

Types of Tests

The two standard allergy blood tests are radioallergosorbent (RAST) and enzyme-linked immunosorbent assay (ELISA). Although the tests are alike in many ways, most veterinarians prefer ELISA, because it provides a more accurate diagnosis. Each one draws a blood sample from the dog, which is sent to a lab for screening. The screening tests the blood for reaction to certain environmental irritants, such as pollen, grass and mold. While the test also can assess possible food allergies, its results are less reliable. It can take several weeks for pet owners to know the results of the tests.

Benefits

The blood test identifies the allergens, so the dog can receive proper treatment and live an allergy-free life. An atopic dog can be treated with regular allergy shots that contain small amounts of the irritant to help him build tolerance and diminish its effects upon exposure. Steroids and antihistamines can lessen symptoms of seasonal allergies. Knowing what the dog is allergic to enables dog owners to limit or avoid the dog's exposure to the irritant, preventing an allergic reaction altogether.

Considerations

Blood tests today are more accurate than those used in the past, but these tests are still subject to false positive results---meaning they can indicate your dog is allergic to irritants he may not be. For this reason, some veterinarians prefer other methods to test for allergies.
Nevertheless, allergy testing is a valuable diagnostic tool for pets suffering from seasonal or year-round allergies when the dog doesn't respond to other efforts such as food trials. It may be necessary to seek out a veterinarian trained in allergy testing and repeated testing may be required to evaluate changes to irritant sensitivity in the dog over his lifetime.

References

• Pet Education: Allergy Testing & Immunotherapy in Dogs