Vaccine for Horses with Insect Bite Hypersensitivity

Despite the fact that 10% of the world’s horses and up to 60% of Australian horses suffer from insect-bite sensitivity, a cure has been elusive. A team of veterinarians recently reported it has created an effective vaccine against insect-bite hypersensitivity.

According to the researchers*, “insect-bite hypersensitivity is the most common allergic dermatitis in horses.” Classic signs of sensitivity, caused by feeding behaviors of Culicoides spp., include hair loss; crusting, thickening, bleeding, and weeping of the skin; and ulceration of the skin caused by inflammation and severe itching.

“Secondary infections can develop from horses scratching and rubbing their skin, causing additional irritation and damage that require veterinary examination and treatment,” noted Laura Petroski, B.V.M.S, a veterinarian for Kentucky Equine Research.

Because of the allergic nature of the problem (the body’s own immune system overreacting to a stimulus), researchers looked at blocking interleukin-5 (IL-5). Interleukins are a class of inflammatory mediators, and IL-5 is currently recognized as the “master regulator” of eosinophils—inflammatory cells involved in allergic reactions.

Vaccinating horses with a molecule that can inhibit or “dampen” the action of IL-5 would minimize reactions to bites from Culicoides spp. that occur secondary to the actions of overzealous eosinophils, researchers theorized.

“The vaccine was well tolerated, did not reveal any safety concerns, and did successfully induce the production of antibodies to block the action of IL-5,” Petroski relayed.

The vaccine also resulted in a clinical improvement in skin disease. In fact, 47% of vaccinated horses had a 50% clinical improvement (itchiness, scabbing, and other signs decreased by 50%), whereas only 13% of unvaccinated horses with insect-bite hypersensitivity demonstrated clinical improvement.

The vaccine is not currently approved in the United States but offers hope to owners with affected horses. While awaiting government approval, consider nutritional supplementation with natural anti-inflammatory products such as the water-soluble vitamin E formulation Nano•E and omega-3 fatty acids found in EO•3. Omega-3s are research proven to help with skin problems, including insect-bite hypersensitivity.

“Kentucky Equine Research also offers hoof and coat supplements, which contain nutrients such as biotin, methionine, zinc, and iodine that support superior skin and coat health,” advised Petroski.

*Fettelschoss-Gabriel, A., V. Fettelschoss, F. Thoms, et al. Treating insect-bite hypersensitivity in horses with active vaccination against IL-5. The Journal of Allergy and Clinical Immunology. In press.