Allergy Testing in Dogs
Does your dog scratch incessantly every springtime? It might be allergies. Instead of subjecting your pet to the deleterious effects of repeated steroid treatments, why not find out what he is allergic to. Then you can have a medication specially made to help reduce the allergies, and to keep your dog healthy and happy.
Currently, there are three common methods used to determine what your pet is allergic to.
Elimination Diet Trial
If the allergy is caused by part of your pet's diet, an elimination diet trial will usually reveal the culprit food. Since food allergies take repeated exposures to the allergic substance, feeding your pet a diet composed of items your pet has never been exposed to may diagnose the allergy.
There are several prescription diets available with the express purpose of assisting in diagnosing and treating food allergies. These diets are comprised of various substances such as lamb, rabbit, kangaroo, whitefish, duck, venison and potato. If your pet improves while on the elimination diet, food allergy is diagnosed. Then each part of the pet's normal diet is introduced individually. Once itchiness reoccurs, the cause of the allergy is determined, and you could avoid feeding that substance to your pet.
The elimination diet trial has a few disadvantages. You must be diligent and not feed your pet anything other than the prescription diet. The entire family must be involved and agree to follow the feeding restrictions. Another disadvantage is that diagnosis can take weeks to months to find an answer, providing the answer is in the food. Sometimes, the elimination trial determines that the allergy is not related to the food. Also, during the elimination diet trial, no steroids can be used and your pet may be quite itchy throughout this period.
Intradermal Skin Testing
If the elimination trial is not effective or it is suspected that the allergen is not food related, intradermal testing may be in order. This common test is considered the most accurate since there are few false positives, except for dust mites. Unfortunately, this test requires someone with expertise to interpret the results accurately. Also, prior to performing the test, all treatments for allergies must be discontinued for weeks to months.
In order to perform the intradermal skin test, a patch of hair is shaved and small markings placed on the skin in a specific pattern. At each pen mark, a specific substance (potential allergic substance) is injected. Twenty-four to 48 hours later, the skin is examined and signs of allergy are determined. Though not 100 percent sensitive, most allergies can be determined by this test.
Blood tests to detect allergies are becoming increasingly more popular since they do not require special expertise and are quite simple and convenient to perform. The disadvantage is that these tests can result in false positives, resulting in treatment for an allergy that does not exist.
The test works by measuring a specific immune substance, IgE, in the blood. It is suspected that if the IgE is significantly elevated in relation to a suspected allergic substance, the pet is allergic to that substance. The test's disadvantage is that even if the IgE level is increased in the blood, it does not necessarily mean there is enough to cause an allergic reaction. This is how false positives occur.
There is no overall best test that picks up every allergy. Some non-allergic pets have had positive test results with intradermal testing as well as with serum tests. Also, some severely allergic pets have tested negative on both tests. The best test may be a combination of both. If found positive on both, the pet is most likely allergic to that substance.
After determining the cause of the allergy, specific treatment can be formulated. Typically, a "vaccine" is developed with the allergic substance. The pet is periodically injected with a low level of the allergen in an attempt to reduce slowly the pet's sensitivity to the allergen. Eventually, many pets respond, and the itching is drastically reduced, avoiding the negative aspects of steroid treatment.