A research group based out of Switzerland demonstrated the effectiveness of treating insect-bite hypersensitivity (IBH) with a vaccination protocol. IBH is the most common allergic skin condition seen in horses today, with breeds like the Icelandic horse as well as our own Friesian breed suffering from this condition. IBH is caused by the bite of the Culicoides midge and results in an allergic inflammatory condition in the layers of the skin. The horse will become very itchy and will often find ways to scratch at the affected areas to the extent that hair loss and open sores will result. This is a chronic disease and one that is not easily treated.
During a previous study, these researchers developed an IBH vaccine by injecting the allergens (obtained from the saliva of the biting midges) directly into the lymph nodes of test horses to help them develop immunity to these allergens. In this new study, 34 Icelandic horses were divided into two groups, with one group receiving the complete vaccine and the other group receiving a placebo (a vaccine without any active components). The vaccinated group showed significant improvement, with a reduced allergic reaction as measured by the size and number of skin lesions and hair loss, compared to how these same horses had been the previous year as unvaccinated horses. The placebo group did not show the same improvement level.
This vaccine is a novel vaccine in two ways: it is the first successful immunotherapeutic approach to treating chronic disease in the horse, and because the vaccine targets a particular cell involved in the inflammatory response (eosinophils) rather than a specific allergen, the vaccine is not allergen-specific so will work across several IBH allergens.
This new vaccine could potentially reach the commercial market as early as 2021, provided continual testing proves its safety and efficacy. Anyone who has owned or managed a horse with this condition recognizes how difficult it is to keep the horse happy and comfortable. It is stressful for both the horse and the owner. Being able to administer a vaccine that not only improves the horse’s comfort but also its quality of life is an amazing accomplishment.
Scientific Article: Fettelschoss-Gabriel A. et al. Treating insect-bite hypersensitivity in horses with active vaccination against IL-5. J. Allergy Clin Immunol 2018 Mar 28.
Companion Article: Lest’e-Lasserre, MA. Novel IBH Vaccine for Horses Tested. theHorse.com, Aug 28, 2018