Any lameness can be tough for a veterinarian to treat and resolve, but pastern joint lameness caused by osteoarthritis can be especially problematic. Stephanie Caston, DVM, Dipl. ACVS, discussed possible options for managing pastern osteoarthritis at the 2010 American Association of Equine Practitioners Convention, held Dec. 4-8 in Baltimore, Md. Chemical joint fusion using ethyl alcohol was one treatment she and colleagues examined in a recent study.
A radiograph of a pastern joint with a needle (circled) in place in preparation for an ethyl alcohol joint injection.
In low-motion joints, sometimes the solution to lameness troubles is physiologic fusion (fixation of the joint so it can't move) called ankylosis, to relieve pain and discomfort. Ankylosis occurs naturally in some joints, but Caston noted that ongoing joint disease in itself is unlikely to result in complete ankylosis. Typically, veterinarians manage such low-motion joints using arthrodesis (surgical fusion) with a variety of approaches ranging from lag screws and plates to drilling away the cartilage to laser surgery or chemical injections with irritating substances (to induce fusion). Many of these orthopedic solutions are expensive and fraught with long recovery periods.
Caston presented an alternative chemical approach to surgical arthrodesis, injecting sterilized 75% ethyl alcohol (Everclear grain alcohol) into an osteoarthritis-affected pastern joint. She and her colleagues selected horses for the study based on a lameness exam, diagnostic nerve blocks, and radiographs scored as to severity of pastern osteoarthritis. They considered treatment successful based on whether the horse was able to return to its previous performance level and on the satisfaction of the owner regarding the horse's use.
Following joint injection with ethyl alcohol, each horse was allowed free-choice turnout. All pastern joints were reinjected with ethyl alcohol one month later. The study included 21 horses and 23 joints with a mean duration of lameness of 13 months; duration of lameness ranged from two months to four years. Of 21 horses, 19 returned to some level of use following treatment. Caston reported that 13 horses returned to their previous level of work or use, five to lighter use, and one returned to work but was euthanized for an unrelated orthopedic injury. Two horses did not respond well to treatment, with one owner opting for surgical arthrodesis after six months and the other electing euthanasia.
The research team noted few complications with this procedure. They observed transient lameness in two individuals and one developed cellulitis (a bacterial infection of the skin and associated tissues) due to suspected septic arthritis.
Caston noted that owners of seven horses with other concurrent orthopedic concerns had elected not to pursue surgical arthrodesis of a single joint, preferring ethyl alcohol injection. She commented that the decision to pursue ethyl alcohol arthrodesis was driven by economics--this procedure is easily performed in a standing horse in a manner similar to standard intra-articular injections. It is also possible to treat two joints concurrently (the veterinarian doesn't have to treat one joint for a while, wait, then treat the other). The period of convalescence before a horse returns to use is shorter than with other surgical options, making ethyl alcohol arthrodesis an attractive alternative procedure, she said.
In some cases Caston noted an immediate and rapid onset of improved comfort. Return to soundness is slower than achieved by some surgical options, requiring a mean duration of eight months. However, this recovery is achieved with a markedly reduced expense. For all horses, Caston remarked that in the horses that were able to return to work, the cosmetic outcome was acceptable.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.