Question

I have a 13-year-old Quarter Horse gelding that I’d like to start on a hoof supplement because he has shaley, poor-quality hooves. I am hesitant to start him on Bio-Bloom PS, despite an ingredient profile I admire, because he tested positive in a blood test for the following feedstuffs: barley, corn, cottonseed, flax, oats, soybean, and wheat. He is not being fed any grain or manufactured treats. He goes out to pasture about 5-6 hours/day and has plenty of timothy hay when in his stall. He is engaged in light-medium work, 3-4 days/week.

Answer

Bio-Bloom PS contains soybean, one of the feedstuffs on the list you would like to avoid.

However, regarding the allergy testing you described, I want to caution you about putting too much faith in these results without first trying an elimination diet. Nutritionists usually do not eliminate a feedstuff based solely on serum allergy testing but instead assess clinical signs.

You will find a lot of conflicting information on the internet and elsewhere about allergy testing. One of our experienced nutritionists, Katie Young, Ph.D., has discussed the overwhelming inaccuracy of dietary allergy testing in horses, especially if it is through blood and not an elimination diet. The American College of Veterinary Dermatology has stated that serum allergy tests are not valid for diagnosis of food allergies. Food allergies are considered quite rare in horses, and environmental allergies are much more common.

Serum allergy testing has been shown to produce many false positives, typically including common feed ingredients such as soy, flax, and wheat. In the rare cases of true food allergies or sensitivities, it does make sense to avoid that feedstuff, but an elimination diet is the only effective method to truly determine whether a feed ingredient needs to be avoided. If eliminating an ingredient results in disappearance of allergic symptoms, such as hives, and reintroduction of the ingredient triggers the allergy response, then that ingredient should be avoided.

Without proper supplementation, his diet is almost certainly deficient in key nutrients and that could be contributing to poor hoof quality. At minimum, you should consider a high-quality vitamin and mineral supplement to properly fortify his diet.