I'm a lab tech for humans and they can do allergy tests on human blood so I don't see why they wouldnt be able to do it on animals. Having allergies means that you have anitbodies in your body that attack the antigens (things in dander, pollen, food, ect...). Not everyone has these antibodies in their system this is why some people are allergic to say dogs and some arent. The way they do the blood test is introducing these antigens into the patients blood and look for a reaction, if there is a reaction then you're allergic to it. I hope that wasn't too scientific or confusing. Good luck with everything
