Q: I have an 18-year-old Quarter Horse that was diagnosed with bone spavin a couple of years ago. He's been comfortable with traditional protocol until recently. I've started him on hock injections, but now they are not as effective. He is very active in both performance and gaming events.

What I understand is that once the lower hock joint fuses the horse is no longer in pain and it usually doesn't change the horse's gait, or slightly at the very least. I read the study which was done regarding alcohol joint fusion and its effectiveness on the disease. I want to make an educated choice for my horse, and this sounds too good to be true. I've mentioned it to my vet, and he says he doesn't like to destroy joints if he doesn't have to. Isn't that what is happening now with this disease (osteoarthritis)? Is this a good choice or should I stay with the traditional treatments?

Karen Daugherty, Toledo, Ore.

A: The first point is that an 18-year-old competing Quarter Horse is fantastic and a testament to the care he has received over his lifetime. "Hock injections" tend to be steroid-based (with or without a disease-modifying agent such as hyaluronic acid) and as such are potent anti-inflammatory drugs. However, the degree to which they act and the duration over which they act in an individual horse are dependent on the stage of the disease, the amount of exercise (or work), and the horse himself. These drugs might slow the progression of arthritis, but they will not stop it, and therefore over time these type of medications tend to become less effective.

Bone spavin is osteoarthritis of the small hock joints (namely the tarsometatarsal and the distal intertarsal joint), and as you correctly understand, once these joints fuse there is no movement and, thus, no pain. It is important, however, to ensure that the disease is limited to these joints and has not progressed into the tibiotarsal joint (the major motion joint of the hock). The small hock joints in an affected horse are being destroyed slowly by the disease process, and depending on the type and frequency of intra-articular medication this process may actually be sped up by treatment due to the medication and the fact that the horse feels good enough to work hard on a degenerative joint.

I have injected 45 horses (personally) with intra-articular alcohol in North America, Europe, Australia, and South Africa. To date, the success rate has been very good. No doubt there is an even larger number of horses being injected than have been reported, but as yet I have not heard any negative reports. This said, no treatment is 100% effective, and there is a chance there are treatment failures in the horse population that the veterinary profession has no knowledge of. A recent paper from U.K. researchers also reported on intra-articular ethyl alcohol treatment for bone spavin, and while their success rate was not as high as ours (for unknown reasons) they reported sufficient success to continue using the technique.

It is very important to ensure that the disease process is limited to the small hock joints as we cannot fuse the higher motion joints. Currently, I am suggesting that my clients treat their horses with intra-articular steroids until the horse no longer responds, then I fuse the joint with alcohol. There are two reasons for this: First, we do not have 10 or 15 years of experience with this treatment, so our case numbers are relatively low. Initial reports are exciting but we need more numbers and more time to be able to state clearly to owners that this is a safe, effective, long-term treatment. Second, at the point where steroid treatment fails, you (the client) do not have any other option; either you retire or euthanize the horse. At this point, if the treatment (fusion) helps the horse short- or long-term, you succeed. And if it does not improve the horse (which is unlikely) then you have lost nothing.

About the Author

James Carmalt, MA, VetMB, MVetSc, FRCVS, Dipl. ACVS, ABVP

James Carmalt, MA, VetMB, MVetSc, FRCVS, Dipl. ACVS, ABVP (Eq), is a professor in equine surgery at the University of Saskatchewan.

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