Bone Spavin Researchers: Alcohol Joint Fusion Effective (AAEP 2010)

Bone spavin in horses, or osteoarthritis of the distal tarsal (lower hock) joints, is a "common cause of equine lameness, resulting in lost training days and limiting affected horses' careers," says James Carmalt, MA, VetMB, MVetSc, FRCVS, Dipl. ABVP, ACVS, associate professor of Large Animal Surgery at the University of Saskatchewan, in Canada. He discussed the results of a recent small study on fusing those painful lower hock joints at the 56th annual convention of the American Association of Equine Practitioners, held Dec. 4-8 in Baltimore, Md.

Joint Fusion

A joint fused with ethyl alcohol.

"Usually these horses are managed with non-steroidal anti-inflammatory drugs (such as phenylbutazone, or Bute) initially, and/or corticosteroids," Carmalt said. "But there comes a time when medical management is no longer working and you need to think about doing something more permanent or retiring the horse completely."

Often when a joint is arthritic and painful, fusing that joint (stopping its movement entirely) will also stop the pain. In the small lower hock joints, which have very little movement, fusion usually does not even affect the horse's gait. Surgical fusion with hardware could be effective, but Carmalt and colleagues investigated the value of injecting common ethyl alcohol into the lower hock joints of horses with clinically apparent bone spavin to induce fusion (this approach was found effective in normal, or non-affected, horses in another study). The researchers were very careful to inject only lower hock joints that did not communicate (share fluid with) other joints, to avoid fusing more joints than intended.

Investigators placed 3 mL of 70% ethyl alcohol placed in the sore lower hock joints of 11 horses for the study, and they re-examined the animals every three months for one year. During this time, the horses went right back to work and no arthritis medications or anti-inflammatory drugs were permitted. After that year, 10 of the 11 (91%) were sound and the remaining horse had lameness graded 0.5 of 5 (on the AAEP lameness grading scale). Ten more horses were treated in this manner by owner request, and seven of those went sound (two remained Grade 1 lame, one with upward fixation of the patella; and one was lost to follow-up).

"Rapid, sustained reduction in lameness" and collapse of the joint space (fusion) occurred throughout the yearlong follow-up period, and Carmalt reported no injection complications, no need for re-injection in any horses, and no white hairs/scarring at the injection site. He also noted that in one horse followed to three years, there was still no lameness. The team plans to recheck the horses at five years post-injection.

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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