AAEP Hot Topic: Less Painful Joint Fusing

Canadian researches find that ethyl alcohol may be used to alleviate the prolonged discomfort of joint fusing. From the editors of EQUUS magazine.
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In August 2006 EQUUS magazine reported on new research addressed at the American Association of Equine Practitioners convention held in San Antonio, Texas, in early December 2006. Check out the full story below.

A discovery by Canadian researchers may take some of the pain out of chemical arthrodesis, a technique commonly used to fuse damaged distal (lower) hock joints.

In arthrodesis, the cartilage of a joint is removed and the bones are encouraged to remodel into a solid, immobile--but painless--mass. Fusing can be accomplished surgically, with implantation of plates and screws, with laser surgery or by the injection of caustic chemicals.

"The current chemical of choice for arthrodesis is monoiodoacetate, called MIA," says Ryan Shoemaker, DVM, of the University of Saskatchewan. "It works well in that most joints will eventually fuse, but in my experience and opinion, the process can cause prolonged discomfort for the horse until that happens."

Searching for a better option, Shoemaker's team turned its attention to ethyl alcohol. "This is the alcohol found in many liquors and now even gasoline," he says. "In the equine world, it has the unfortunate distinction of being what was injected into horses' tails to illegally numb them for the showring."

Shoemaker was familiar with the benefits of ethyl alcohol in cattle suffering from prolapsed uteruses after calving. "Food animal veterinarians occasionally will do a low spinal block with ethyl alcohol on these animals to freeze nerves and take away all sensation so we could fix the problem," he says. "It's pretty powerful stuff."

To test the potential application of ethyl alcohol in arthrodesis, the researchers injected one hock joint on eight horses with a 70 percent solution and the other with a 95 percent solution. They performed lameness exams daily for two weeks and then monthly for the following year. The joints were radiographed one month after treatment and every three months thereafter so that signs of joint fusion could be charted.

"What we found was very encouraging," reports Shoemaker. "The joints fused as well or even better than with MIA and the horses had minimal or no lameness associated with the treatment." He adds that injections of ethyl alcohol under the skin of the horse "to see what might happen if someone missed the joints" led to very local and minimal irritation.

Further study is needed, says Shoemaker, but "from what we know now, this is a way to get the job done while putting the horse through the least amount of discomfort."

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