Vapocoolant Spray Reduces Joint Injection Pain

While humans might utter an "ouch!" when poked with a needle, horses' reactions can be much more physical. A needle, joint injection(s), or intravenous catheter can result in kicks, bites, and other less-than-desirable behavior from a horse. But according to two Norwegian veterinarians, applying a vapocoolant spray (sprays that cause a short-lived anesthetic effect on the skin surface) before these procedures appears to decrease anticipation of pain and actual pain for the horse and improves the veterinarian's safety.

"Studies in human medicine show that there is a significant reduction in pain when a vapocoolant spray is applied to the patient, either adult or juvenile, before performing an intravenous catheterization," said Cathrine Fjordbakk, DVM, from the Department of Companion Animal Sciences at the Norwegian School of Veterinary Science in Oslo.

"The efficacy of vapocoolant sprays during minor medical procedures has not yet been studied in horses," explained Fjordbakk. "In equine practice most horses tolerate these procedures well, but some horses resist the procedures to such an extent that it is unsafe for the horse, the veterinarian, and the assistants."

To evaluate whether vapocoolant spray was effective in horses, the researchers sprayed eight healthy, unsedated horses with either a commercial vapocoolant spray or placebo (water) at the injection sites (the knee and ankle joints, and the jugular vein). A single observer who was blinded to the type of spray scored the horses' responses to the injection using two separate scoring systems. The first system was a six-point categorical scale (0=no response, 5=severe response) and the second was a 100-mm visual analog scale (0=no response, 100=worst possible response).

"This study found that the horses' responses were significantly lower when the vapocoolant spray was used before injecting the knee and ankle joints, but no difference in pain scores was detected for intravenous catheterization of the jugular vein," summarized Fjordbakk.

"The spray was effective and could improve the safety of personnel performing diagnostic joint injections," Fjordbakk continued.

Considering the low cost, ease of use, and lack of adverse effects, using a vapocoolant spray in horses prior to joint injections in unsedated horses might be a welcome addition to any veterinarian's arsenal, the researchers suggested.

The study, "Effect of topical vapocoolant spray on response to arthrocentesis and intravenous catheterization in unsedated horses," was published in the June 2011 of the American Journal of Veterinary Research. The abstract is available on PubMed.

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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