EQUINE ALLERGY

THE GROWING ACCEPTANCE OF TESTING AND SUBSEQUENT TREATMENTS

HORSE HIVES circleBoth allergen-specific immunotherapy (ASIT), and the use of environmental serological testing as an aid to the diagnosis of atopic dermatitis, are clinically well accepted within canine practice 1. This is not currently the situation for equine allergy cases, although ASIT in horses is becoming a much more accepted and frequently conducted treatment, with the benefits discussed at the World Congress of Veterinary Dermatology in Bordeaux last year 2,3.

Dr. Yu, who presented in Bordeaux, wrote in the proceedings of the American Association of Equine Practitioners convention 2015, these take home messages; 1) “Treatment of equine allergies requires a multi-modal approach including environmental control, topical, and systemic therapy, and allergen-specific immunotherapy”. 2) “Allergen-specific immunotherapy should be considered for all presentations of equine allergies including hives, heaves, scratches, and head-shaking as it is a cost-effective weight independent treatment option that is not banned by the FEI, has minimal adverse effects, and may eventuate a cure”.4

To enable ASIT, and also allow targeted avoidance, problem allergens first need to be identified. Much of the recent literature states that either serological testing or intra-dermal skin testing are acceptable methods for equine allergen detection in atopic dermatitis, respiratory allergies and insect bite hypersensitivity (IBH).2,5,6,7

Similarly to canine allergy diagnosis, judicious interpretation of either test result is critical as Marsella (2013) states; “the single most important aspect in formulating a successful immunotherapy is not which test is used but how the allergens are selected (i.e., emphasis is placed on correlating the results with the seasonality and environmental exposure of the individual patient to increase the likelihood of including clinically relevant allergens among the ones that tested positive”)8. With the recent advent of more relevant allergens available through our serological test (UK and Northern European panel), it is hoped more horses will now benefit from ASIT.

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(1) Olivry, T., DeBoer, D.J., Favrot, C., Jackson, H.A., Mueller, R.S., Nuttall, T & Prélaud, P. (2015). Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee
on Allergic Diseases of Animals (ICADA). BMC Veterinary Research, 11:210
(2) Mueller, R.S., Janda, J., Jensen-Jarolim, E., Rhyner, C. & Marti, E. (2016). Allergens in veterinary medicine. Allergy 71: 27-35
(3) Loewenstein, C. & Mueller, R.S. (2008). A review of allergen-specific immunotherapy in human and veterinary medicine. Veterinary Dermatology 20(2): 84(15)
(4) Yu, A.A. (2015). Treatment of Equine Allergies. In: Proceedings of the 61st American Association of Equine Practitioners convention, Las Vegas, 2015
(5) Fadok, V.A. (2013). Update on equine allergies. Vet Clin North Am Equine Pract. 29(3): 541-550
(6) Jensen-Jarolim, E., Einhorn, L., Herrmann, I., Thalhammer, J.G. & Panakova, L. (2015). Pollen allergies in humans and their dogs, cats and horses: differences and similarities. Clinical and
translational allergy 5:15
(7) Stepnik, C.T., Outerbridge, C.A., White, S.D and Kass, P.H. (2012). Equine atopic skin disease and response to allergen-specific immunotherapy: a retrospective study at the University of California
Davis (1991-2008). Veterinary Dermatology, 23(1):29-3
(8) Marsella, R. (2013). Equine allergy therapy: Update on the treatment of environmental, insect bite hypersensitivity, and food allergies. Vet Clin North Am Equine Pract. 29(3): 551-557