Friday, September 28, 2012

How Research Works: Sport Horse Suspensory Ligament Study Involves Real Dressage Horses and Riders

A call for dressage riders offered a free analysis of joint motion, rein tension and  rider balance  in exchange for riding a horse of a specific age and dressage level on two different arena surfaces. The researchers are gambling that dressage riders will want to be part of equine research that targets the function of the suspensory ligament, one of the most common sites of lameness in dressage horses. (AHT photo)

You read the research. You look at the data. You note the summary.

But did you ever want to know more?

Researchers often list their protocols, including the number of horses or cases evaluated. Some will give some data about the horses--sex, age, use--but that may not tell you much.

If you've ever been to a vet college, you know that they often have a herd of research horses. Some are more athletic looking than others. Some are more sound than others. Some are all one breed, while at others, the herd is made up of mixed breeds. At some schools, the horses in the "research herd" look like they are seen by a farrier about once a year.

When you read about sport-related research, you trust that the research was actually done on sport horses. Most researchers will now give much more background data on the horses used in the trials, because they know this is necessary for the credibility of their findings.

Unfortunately, the numbers of horses in studies is usually small because of the difficulty in obtaining horses to test and the labor-intensive aspect of equine research. Large retrospective studies of cases are possible for injuries, but what about when the subject is gait analysis or sports performance?

And even for studies that are data analysis of cases treated at a university or vet hospital for a certain condition, or treated by a certain procedure, a considerable number of cases are lost to follow up because they were sold, died or the owners didn't answer a researcher's questions.

So an announcement that was circulating on the internet seemed interesting. The Animal Health Trust (AHT) in Newmarket, England has done several studies on injuries to the suspensory ligament. In fact, the letters PSD--for proximal suspensory desmitis--are closely connected with the letters AHT.

The suspensory ligament (sometimes called the interosseous) is show in white; it is a common site of lameness in performance horses.  Jumping horses commonly injure the branches of the ligament, shown at right, but the ligament can be injured at any point along its length and in either of its branches. (Illustrations are 3-D animations from Glass Horse: Elements of the Distal Limb)

The Animal Health Trust is known for taking a rider-centric view of equine lameness. The rider may be asked to school the horse as part of the lameness exam. That may not be enough to satisfy clinician Sue Dyson, who has trained horses at the elite level of eventing and ridden Badminton herself. She employs a professional rider to participate in the lameness evaluation so that the rider's balance, ability or mental state can be ruled out as influencing the horse's gait.

The first line of the announcement read:

"Would you like to get a free assessment of your horse’s gait, symmetry and exercise programme with your travel costs covered? And also help prevent suspensory ligament injury in dressage horses for the future?"

If you think like an equestrian, that sounds like a pretty good deal, with a feel-good factor thrown in for good measure.

But from someone who follows sport horse medicine, it could only get better when the study was outlined in this way:

"The Animal Health Trust is looking for horses and riders to be filmed at trot using high speed video on two different (but good quality) arena surfaces as part of an important investigation into suspensory ligament function in horses of different levels and with different types of movement.

"For the project we are looking for combinations which fit into the following groups and would be willing to travel to Keysoe, Bedfordshire (travel costs would be covered) on 8th, 9th, 12th or 13th November and can allow approximately two hours for the testing, from arrival until completion."

Remember the comment about some horses used in studies being sketchily described in the papers?
Consider this precise description of exactly what horses were being sought for this study:

1. Young horses (seven years old and under)
• Very extravagant moving (achieving scores of 7 or 8 and above for paces) or
• Less extravagant moving (achieving scores of 6 or less for paces)

2.  Mature horses (10 years and above), training at advanced level (working Intermediate 1 and above)
• Very extravagant moving (achieving scores of 7 or 8 and above for paces)
• Less extravagant moving (achieving scores of 6 or less for paces)

The requirements don't just describe the qualities of the horses needed. It also describes what the rider needs to be prepared to do.

"Horses will need to be ridden by their normal riders in a straight line in collected/working, and medium/extended trot (and piaffe and passage for any horses trained to that level) on two different surfaces."

For their effort, the riders are to be reimbursed for their travel expenses (remember that British gas is at least twice what it costs here in the USA) and this promise of a report:

"Feedback for the rider will include information on the gait (including joint flexion angles) and symmetry of the horse, rein tension, and rider position, plus advice on exercise programmes and performance if the rider would like this information."

I can't think of any dressage riders who wouldn't like that information.

The closing message rolled out the feel-good factor:

"The results of this study would enable us to provide immediate and beneficial advice on training practices to dressage trainers, riders and owners, in order to reduce the risk of suspensory ligament injury.

"Based on the number of horses that suffer from suspensory ligament injuries, and the variable outcome of treatment/management, any work which improves prevention strategies would have a considerable positive effect on dressage horse welfare."

What the text doesn't mention is that the Animal Health Trust is a charitable organization that depends on donations. By inviting and potentially involving citizen dressage riders to participate in the study, the AHT is opening the door for future donations from the riders and also creating a culture of transparency and awareness of the dressage community's problems with suspensory lameness.

When the study is complete and the researchers publish their findings, the British dressage community will have a sense of knowing the horses and riders who participated and of having been part of some important research. Everyone reading the study will know exactly what level and type of horses were in the study.

If you live in England and would like to be part of the study, you can apply by sending an e-mail to; telephone: 01638 751908 or 07825 005125.

Vicki noted that horses from the local area will be accepted first to try and minimise travel expenses.

To learn more:

All about suspensory ligament injuries by Sue Dyson FRCVS
Suspensory Ligament Injuries in Horses, a UC Davis Center for Equine Health special report (free PDF download).

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