The allergy test showdown: Skin vs blood testing

In this episode of Vet Watch, we dive into the essentials of veterinary dermatology with our host Christopher Lee, DVM, MPH, DACVPM, and special guest Alice Jeromin, DVM, RPh, DACVD. Throughout the episode, Jeromin shares her insights into the effectiveness of serum and skin testing for allergies pets through what the research and data says, and discussing how the opinions on it can differ between veterinary dermatologists, plus she puts an emphasis on the importance of proper interpretation of the pets history and if seasonal factors could be at play, and more.

Below is a partial transcript, edited lightly for clarity

Christopher Lee, DVM, MPH, DACVPM: Now, am I oversimplifying things? But it seems to me that there's kind of 2 ways of thought for a lot of general practitioners. Those that say I like doing the blood tests if they want to go to a dermatologist, great, but maybe that is not an access for many of their clients, so they're doing in house. And then you have another group that say, my dermatologist does not like the serum testing. We don't believe in it, so the only way to do is skin testing. Is that kind of the two groups of thoughts that you see.

Alice Jeromin, DVM, RPh, DACVD: I do, except there's a subset of the dermatologists that say, "gold standard" for intradermal skin testing. And well, let's, let's broach that first. After having a long career in pharmacy, I saw so many drugs that were the gold standard come and go, and I think you'd agree, in veterinary medicine, you know, 15-20 years ago, there were drugs that, oh, they're outstanding, and that's our standard. And now the not so much. So I like to refer to it as the current standard of care and having said that, you can ask 10 veterinary dermatologists and get 10 different opinions. My personal opinion is I like to skin test and serum test because I figure that gives me all the information I can get that I need to make up that allergy solution. It's not for me to make that diagnosis of atopy. That's for sure. We're going to talk about that and and again, the reason the gold standard is not skin testing or serum testing is you can have non allergic pets skin test or serum test positive, and vice versa. You know.

Lee: Now that's, that's one of the things I hear often, is that if non allergic. Dogs or people. So if you do not have atophy, you could run a serum test and just pop up positive for a lot of things. And many times I hear that is the reason as to why they do not believe in that testing.

Jeromin: I gotcha. And that's also true for skin testing, of course. Why would I be skin testing a clinically negative patient for atophy right? But in tests that have been done in the past for people publishing papers, you can have clinically normal let's we're going to, let's say dogs, and you skin test them and you get positives. There are reasons for that, but certainly it's kind of like Cushing's disease. If there's no symptoms for it, why am I going to treat it? You see what I'm saying.

The other thing I wanted to tell you about IgE driven. You know, it's interesting, because in people, when they're trying to diagnose at being people, this was a long time ago, they would do total IgE levels. And they would find that in children, those total IgE levels, if they were elevated, usually meant that kid's going to become a topic as it gets older. Well, they did that same test for dogs, didn't pan out at all. They did IgE, total IgE levels in puppies followed them out for 3 years. Made no difference. Some of the atopic dogs had the same levels as the non atopic. So IgE, even though we've isolated it in dogs and we have ways to go in cats, we still have a long way to go. Long ways to go. That's why we can't use the serum or skin test to say your pet, your dog, is atopic.

You know, I'll get a client in that says this. Well, this is worst case scenario for all of us. I want to know what my dog's allergic to. Okay, got the dog on the table. I'm combing it. There's a couple of fleas there. Oh my gosh, Mrs Jones, look, did you know your dog has a couple flea? Yeah, I know he's got some fleas. I want to know what he's allergic to that. You know, that's a good hour right there, because you've gotta convince that owner, okay, we've gotta resolve this flea problem, flea allergy first, and then there may be additional allergies. And yes, most atopic dogs are flea allergic, I'll give you that, but it it's difficult for owners to understand that a couple of fleas could be causing all that same problem as, say, a ragweed allergy. I think because they compare it to us, they see how miserable atopy is in us and we don't have fleas. So that must be, what's wrong with the dog must be atopic.