Page 96 - July 2015

Surgery may be necessary for cervical vertebral malformation (CVM) if a myelogram diagnosis indicates cord compression.
we don’t know how much the environment and/or management practices play into this,” he says. There are many things to sort out.
“Dr. Janes (University of Kentucky) reiter- ated what some other researchers have said about gender; wobblers occurs 3 to one in
male horses over female,” says Reed. “She also identified certain genetic areas that people have been looking at, and we are encouraging her to take that data and present it as a model, stating that this is the model we believe is the role that genetics play in CVM,” he says.
The study they are doing in their investiga- tion of wobblers syndrome is broad, looking
at everything from genetics to diet to spinal cord pathologies, along with new diagnostic techniques and imaging availability. “We did a lot of MRI work on post-mortem studies, but there is not yet a magnet big enough to get a live horse’s head and neck in there. We can get part of it into the MRI, but not the entire neck, and it’s not very useful if you can’t do a com- plete evaluation. From a learning point of view, however, looking at the pathogenesis, the MRI studies were an extremely good thing. This showed how many areas can be affected, as well soft tissue changes within the spinal canal that can lead to stenosis of the canal and subsequent pinching of the spinal cord,” Reed says.
“Dr. Janes then looked at the micro CT of the bone to see if there were actually two differ- ent pathogeneses, one starting as developmen- tal osteochondrosis. We also found some new things, including some unique changes in the articular process joints where there were some cyst-like structures that had not previously been reported. These could certainly be associ- ated with abnormal changes in the shape of these joints, which could impinge on the spinal canal and subsequently press on the spinal cord. There were several different types of bone pathology recognized,” says Reed.
“Dr. Janes just completed a PhD on cervical vertebral stenotic myelopathy. She reviewed the work that was done by former graduate students of Dr. Barrie Grant and myself, and work done by graduate students at Ohio State University. Dr. Janes reviewed all of their previous publica- tions and decided what would have been the next step in each of their projects. Her PhD thesis is quite detailed and there are several inter- esting things that she sorted out regarding the bone pathology, for instance,” Dr. Reed says.
Areas in which practitioners are trying to improve include some of the surgical techniques, and picking out which cases might benefit from surgery and which ones won’t. “People who are doing the surgery are realizing that we’ve been interpreting the myelograms too harshly,” says Grant. “Some with mild changes on the myelo- grams are actually the cases we can help the best. We may not have been operating on those horses earlier because we wanted to first have a really
trying to do their job because most horses will keep performing for their riders even when they shouldn’t. Most horses try very hard and when they decide they don’t want to do something, there’s usually a reason,” says Grant.
“Those are the horses that we can now help the most. Some of the mild cases are horses that perform better when their hocks or stifles are injected because they have steroids in the system that help the spinal cord. They may act like they have a weak or sore back, and this may be due to not enough nerve function going to the muscles. When these mild cases are properly diagnosed and we operate on them, they may go back to the top of their career again and are happy doing their job,” he says.
Some horses benefit from having arthritic vertebrae (the facet joints of those vertebrae) injected in the lower part of the neck. “I tell owners that even though the horse might look like he’s off behind, if you can’t find something distinctly wrong in a hind leg, they should be thinking about a neurological problem. Hind leg lameness can be difficult to figure out because sometimes it’s not a hind leg problem,” he explains. It doesn’t hurt to do a quick neuro- logical exam while doing the lameness exam. It only takes a few more minutes to have the horse back up, do some tight circles, pull on his tail, and maybe go up and down a hill.
Many people underestimate what can
be done for some of these horses and how beneficial it can be once you make the proper diagnosis and institute proper treatment. “For spinal cord compression, it’s usually surgery. Sometimes injections of certain facet joints will help. If it’s EPM or herpes virus, you need to
resolve that problem. If vitamin E level is low and the myelogram is negative, the x-rays and tests for EPM are negative, treat the horse with vitamin E. It’s all about getting an accurate diagnosis,” says Grant.
OngOing ReseaRch
Dr. Steve Reed, Rood and Riddle Equine Hospital (Lexington, Kentucky), says there’s research looking into the genetics of this problem, as well as looking at diagnosis and treatments.
“A project at the Gluck Center is looking at the potential role of genetics. I am on the committee that’s working on this. We’ve always considered wobblers to be a multi-factorial disease, and now that we have gene chips, we are finally getting close to some sort of an answer,” he says.
“It probably won’t be simple because of multiple genes involved, but we may learn about something else that could be very helpful. The primary professor working on this research is Dr. Jamie MacLeod of the University of Kentucky, and the principal graduate student was Dr. Jennifer Janes. The genetic aspect of this disease is something that horsemen and geneticists have been interested in for a long time, and now this group—made up of some really good research- ers—is investigating this idea,” says Reed.
“There are certain breeding selections and crosses that a person might not want to make to avoid the risk of producing a wobbler foal,” says Grant. “The opinions on the genetic aspect are split. Some people say the science shows we can’t really say it’s a genetic trait, while other people point to certain stallions that sire more than expected numbers of wobblers. These foals are often on the same farm, however, so
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equine health