Handling of Vaccines for Horses

It's spring: the time of year when we are in the throes of boostering horse immunizations, with the intent to maximize immunity before mosquito season and competition campaigns get into full swing. Many equine vaccines are credited with inferring significant protection to horses against serious and potentially fatal viral diseases. Some horse owners feel comfortable giving shots to their horses, while others rely on their veterinarians to perform vaccinations. Regardless of who administers the injections, there are some important factors to keep in mind.

It is critical that vaccines are stored properly to maintain their efficacy. Purchasing vaccines from a reputable source implies you're acquiring a product that's been refrigerated properly and hasn't lost its potency, and it also suggests it's not outdated. Warehouse or wholesale outlet companies, feed stores, or veterinary bulk supply outlets won't necessarily guarantee proper handling of these products. If you vaccinate with a product purchased from one of these sources, you might not be assured that your horse will receive adequate immune coverage. In contrast, having your veterinarian vaccinate your horse ensures the vaccine comes from a reputable outlet and that it has been managed properly, including maintenance at proper cold temperatures during the transfers from manufacturer to distributor to veterinarian.

If you purchase a vaccine directly from your vet with the intent of giving it yourself, place it in a small cooler immediately with ice packs to maintain the "cold chain" until you can either immunize your horse that day or transfer it to your refrigerator for later use. Tucking vaccine away in a cooler prevents you from absent-mindedly leaving it on your desk at work or, worse, on the dashboard of your truck, in the sun. Heat or excess cold inactivates vaccine components, rendering them ineffective, and lack of potency is not always apparent with visual inspection. You should not administer a vaccine that has not been maintained consistently at refrigeration. Rather, you should dispose of it properly, flushing the liquid contents down the drain and incinerating syringes and/or returning syringes and needles to your veterinarian for medical waste disposal.

Your veterinarian uses safe techniques for administering vaccines that, 1) incur the least risk to your horse, and 2) protect you as much as possible from injury by a fractious horse. Even with excellent injection technique, it is possible for a horse to develop transient side effects, such as muscle soreness, fever, or malaise, and although it's uncommon, a post-injection abscess might occur. Occasional transient reactions are usually related to an immune response to a particular antigen (protein) or a reaction to the adjuvant (the carrier agent) in individual vaccines--some vaccine products tend to be more reactive than others.

Signs associated with adverse reactions typically pass within 72 hours. When you or your vet use quality vaccines, the fact that the horse has received an injection should be apparent in fewer than two or three horses in 100. Based on the sheer number of horses your vet immunizes each year, he or she has knowledge of which manufacturers produce vaccines with the least likelihood of adverse reactions.

Whenever your horse experiences an adverse reaction, let your veterinarian know so he or she can take precautions in the future to minimize the animal's discomfort: Your vet might use a product from a different manufacturer, premedicate the horse with a non-steroidal anti-inflammatory drug, and/or give vaccine antigens at separate intervals rather than all at one time.

It is relevant to keep in mind that if your horse is insured and you (not your vet) administer any medication, including a vaccine, that induces a life-threatening or fatal anaphylactic reaction due to incorrect injection technique, an insurance company might be reluctant to honor your insurance claim.

About the Author

Nancy S. Loving, DVM

Nancy S. Loving, DVM, owns Loving Equine Clinic in Boulder, Colorado, and has a special interest in managing the care of sport horses. Her book, All Horse Systems Go, is a comprehensive veterinary care and conditioning resource in full color that covers all facets of horse care. She has also authored the books Go the Distance as a resource for endurance horse owners, Conformation and Performance, and First Aid for Horse and Rider in addition to many veterinary articles for both horse owner and professional audiences.

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