Today on Texas Vet News I am going to talk about food allergies in horses, which is a fairly unusual problem. Horses with food allergies can have gastrointestinal symptoms, skin symptoms, or both. Dr. Dawn Logas is a dermatologist in Florida and she indicates all food allergies may not be actual allergies, and therefore should be called adverse reactions to food. The term allergy is usually used for simplicity. There are many cases of food allergy that may not be diagnosed, so it is difficult to know the true incidence but almost all foods have been reported to cause allergies in some horses including alfalfa, barley, beet pulp, bran, clover, oats, feed additives, feed supplements, and many others.

Horses with food allergies are usually itchy and will be scratching and rubbing. They may have hives, crusts and hair loss. Symptoms of colic and especially diarrhea can develop. Unfortunately, many other diseases can cause similar symptoms, including mites or lice on the skin, ringworm, and bacterial infections. Also, signs of contact or inhalant allergies will appear similar to those of food allergies. Allergy to flying insects also appear similar to food allergy and is very common, although food allergies occur year round while flying insect allergies and most inhalant allergies are usually seasonal.

The only reliable method to diagnose food allergies is with a food trial. Intradermal skin testing and blood testing are used by many vets, but results have shown to be unreliable in horses and other species. A food trial can be difficult in a horse as a new protein and carbohydrate source in hay and grain must be used for a food trial that lasts 8 to 10 weeks. All supplements must also be discontinued during the food trial. If your horse has unexplained itching, food allergy could be involved.