How can we test my pet for what they are allergic to?
The first point to be made about allergy testing is that testing should only take place after a diagnosis of an airborne allergy is made. A diagnosis is made by clinical signs and your pet fitting many of the criteria that have previously been discussed. The reason that a diagnosis should be made first is testing is not 100% accurate and there is the possibility of false positives. This means that pets without allergies can have positive responses to allergy testing. The second point to discuss before testing is why we are testing. The reason we are performing “allergy testing” is to identify what allergens are causing a problem, so we can make a solution with these allergens to perform immunotherapy. We will talk about immunotherapy shortly.
There are two ways to test for what your pet is allergic to:
Intradermal skin testing (IDST): For this procedure your pet is sedated and a patch of hair is shaved on his/her side. Small amounts of concentrated allergen (pollens, molds, grasses, weeds) extract are then injected under the skin and the reaction to the allergies are measured. Allergens that your pet is allergic to should puff up and become red. In order to get accurate results on these tests your pet will need to be off of antihistamines for a minimum of 2-4 weeks and off steroids for at least 4-6 weeks. This testing does typically require referral to a veterinary dermatologist and the usual cost is ~$380. This is considered the “gold standard” for allergy testing. The best time of year to test is usually in the early fall (Sept/Oct).
Serum antibody testing: This is a different way of testing for allergies in pets. The pros of this test is that it does not require referral, only requires a blood draw, and typically your pet does not need to be off of steroids or antihistamines for testing. The drawback is that you can have some false negative or positive results (this is true for any testing). For this test the amount of antibodies (specifically IgE which is associated with allergies) to specific allergens are quantified. Those allergens with higher antibody levels are deemed the problem allergens. The cost for testing is ~$200.
It is possible with both tests to get negative results (no reaction to allergens). For dogs that obviously have an allergy problem there can be a few reasons for negative tests including:
1. Improper withdrawal of steroids/antihistamines
2. Wrong time of year for testing
3. Improper choice of allergens being testing
If your pet has a negative allergy test, then it may be suggested to try the other type of testing (IDST versus serum testing or vice versa).
My pet had allergy testing performed, now what?
Once your pet has been allergy tested and the offending allergens are identified, then we can proceed to immunotherapy. Immunotherapy involves making a solution that contains small amounts of the different allergens that your pet is allergic to. This solution is then injected under the skin (or more recently placed under the tongue) every few days. There is an initial induction phase (6-10 weeks) where the solution is dilute and then over the next few weeks the amount given and the concentration of the solution are increased. Once we have reached the maintenance phase, your pet will be getting injections every 1-2 weeks. Many dogs (60-70%) show improvement with immunotherapy. This does not necessary mean that the itching symptoms will go away completely. In many cases, pets may need additional therapy (anti-histamines or steroids) during certain times of year, but hopefully the dosage, frequency and length that these medications are needed will be reduced. The improvement are not immediate either. Pets typically take 3-5 months to show improvement and in some cases can take upwards of a year. The cost per year for a typical dog on immunotherapy is ~$620. This therapy is typically continued life long, but in some instances can be stopped after a few years of therapy.