Horse Side Vet Guide ®

Equine Health Resource

Hyposensitization, Allergy Shots



Based on the results of skin allergy testing, a panel of potential allergens is determined. Variable amounts of these allergens are added to injectable solutions to make up a battery of increasingly concentrated “allergy shots.”

These shots are injected in very dilute quantities at the beginning of the treatment course, and gradually the quantities of allergen are increased. The rationale is that these increasing amounts of allergen cause the immune system to become tolerant of the allergen.

To start, the allergy shot is given frequently. After several months, a maintenance protocol is started in which the allergy shots are only given every several weeks.

These injections are called “immunotherapy” because they modulate the immune response to allergic stimulus. Immunotherapy has been used successfully in some cases as a sole therapy in preventing hives. In other cases, hyposensitization injections may reduce the dependence on steroids, which are prohibited in shows and performance events and may also have unwanted side effects when administered long-term.

Immunotherapy may take up to six months for full benefit to be realized, and owners are encouraged to continue therapy for at least one year before discontinuing.

This Treatment Might be used for a horse exhibiting these signsRelated Observations

Consider Potential Side Effects & Complications

In most cases, allergy shots in the horse are considered pretty safe. However, as with any injection, there is the potential for an excessive allergic reaction.

Consider Reasons Not To Use This Treatment

Cost is a consideration. Between skin testing and purchase of the allergy shots, this can be a costly therapy. This is usually used in situations where horses must be treated long-term with steroids to control allergy.

Is It working? Timeframe for effect

An effect should be seen in weeks to several months, with a reduction in the dependence on steroids and signs associated with the allergy.

Questions To Ask My Vet

  • What response should I expect, when?
Author: Doug Thal DVM Dipl. ABVP


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