Page 25 - The Game September 2006

Your Thoroughbred Racing Community Newspaper The Game, September 2006 25
FROM THE HORSE’S MOUTH: HOW BIT FIT AFFECTS COMFORT AND PERFORMANCE
Equine Health
by Karen Briggs
Dave Landry Photo
MANAGING
YOUR
MONEY
With Rick Debattista
Employer-sponsored investment, health, and retirement plans
- it pays to know what's what
Every morning in the backstretch we muck out, saddle up, groom, and feed our horses and we love every minute of every day.
We love our horses and want the best for them. That’s great! This is why we do what we do.
The backstretch offers a quality of life that can’t be found with very many professions today. Kid yourself not you are professionals therefore you deserve to be treated as such and thanks to the HBPA you are.
The HBPA has helped bring Horsemen and women up to par with what some call the outside world, meaning life outside the backstretch by offering eligible pensions, dental, medical coverage and more - much the same as most off track jobs.
But are you making the most of what is available to you?
With my new monthly column in The Game, I intend to provide you with financial information which will help you look into your future and make financial decisions that you may otherwise have neglected. After all knowledge is power.
One of the more often overlooked categories of "labour-derived" income that you should take into consideration are the above mentioned health benefits and investment plans which are available through your employer or in the case of backstretch workers, is offered through the HBPA.
One of the main benefits of joining an Employer Benefit Plan is that they provide valuable insurance coverage and are important sources of retirement income.
But make sure you really know what you're signing up for... or not signing up for?
It is important because there may be gaps in your coverage or you could be paying for benefits you don't need. That is why it pays to periodically evaluate all of your work-related plans and know exactly what each provides. To get you started, here are a few tips:
All work-related plans
• Carefully read the booklets for each of your employer-sponsored plans and be sure you know what benefits you are entitled to receive under each plan.
• Keep track of the benefits informa- tion - especially pension plan statements - from each company you've worked for during your career.
• Read every notice you receive and look carefully for changes. Employers can usually revise or even terminate plans, but they must give you plenty of notice.
CONT. Page 30 - See Rick
Museums are full of them: rusty fragments of snaffle bits, found in archaeological digs along with the remnants of chariots and harnesses from ancient civilizations. The basic design of the jointed snaffle hasn’t changed much over the millennia. Why mess with success, after all? It’s simple, and it works. Or does it?
The human compulsion to build a better mousetrap has led to an explosion of variations on the basic ring snaffle in recent decades. While some are favoured by those with riding horses, many more have made their way into the hands of racing folk, and into the mouths of their horses. Are they all shots in the dark or is there a rationale for one design working better than another, affording both control and comfort?
Renowned equine sports-science researcher Hilary Clayton, BVSc, PhD, MRCVS, of the Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, completed a landmark study in 2004 which examined the way snaffle bits function in the horse’s mouth. With the help of a team including Fred Derksen, DVM, performing endoscopy of bitted horses, Diana Rosenstein DVM, taking fluoroscopes, and University of PEI veteri- nary intern Jane Manfredi, Clayton looked at the anatomical structure of the horse’s mouth to better understand how the bit sits in it, and how the horse interacts with that foreign object he can’t spit out. Then she used an endoscope to look at the swallow reflex and how it changes when a horse is wearing a bridle and bit. Some of her findings may change the way you think about choosing the right hardware for your horses.
The fluoroscope, a kind of radiographic machine capable of making three-dimen- sional, real-time movies of the horse’s inner workings, demonstrated immediately to the MSU team that the horse’s tongue, in its resting state, completely fills the oral cavity. So in order for a bit to fit in the horse’s mouth, something has to compress. Right away, the time-honoured notion that thicker mouthpieces are milder in action than thinner ones was challenged because a thicker mouthpiece is likely to compress more of the tongue, which might not be as comfortable for the horse as accommodating a mouthpiece with a smaller surface area.
Horsepeople all know that the bit sits on the bars of the horse’s mouth, that stretch of bare gum between the horse’s incisors and the first pre-molar. In anatomical terms, it’s called the diastema. Clayton postulated that a longer set of bars (particularly on the upper arcades, where the hard palate forms a barrier between the roof of the mouth and the nasal cavity) might provide more room for a bit to flex and move, and she performed measure- ments, with the aid of the fluoroscope, to determine that the distance between the incisors and the cheek teeth ranged from 71 to 86 mm in her test horses (which represented several different breeds). She found that the length of the bars is not necessarily linked to the horse’s size or height. Likewise, the height of the hard palate, measured from just in front of the lower cheek teeth, varied from 33 to
44 mm, with no relationship to
the size or breed of the horse.
But the height of the mouth
cavity is crucial, Clayton says,
because it determines how fat a mouth- piece the horse can comfortably wear.
The next step in the study was to observe how horses adapted to wearing a variety of snaffle bits, using fluoroscopy to record their movements for 20 seconds at a time on a videotape. (The 20 second limit was imposed to ensure none of the horses or researchers got a radiation overdose.) Eight horses, standing in a set of stocks to limit their mobility, were fitted with open bridles with the snaffles adjusted according to conventional wisdom, with a couple of wrinkles at the corners of the mouth. They were filmed both with no pressure on the bit, and with side-reins attached to approximate the action of the bit with rein pressure.
The bits the MSU team evaluated included a common-or-garden variety single-jointed ring snaffle, a Boucher snaffle with short fixed upper cheeks, a double-jointed or ‘French link’ snaffle, and three other double-jointed snaffles with rollers and ports manufactured by Myler (currently all the rage in the hunter/jumper ring). Regardless of the design, they noted that when a snaffle is in the mouth of a horse, it does not sit horizontally. Rather, it hangs suspended by the cheekpieces · and the central joint pokes into the soft palate on the roof of the mouth, even when there’s no tension on the reins. Depending on the design and the smoothness or sharpness of that joint, this could be tolerable · or extremely uncomfortable for the horse.
In general, Clayton found that double- jointed snaffles appeared to be an improve- ment over single-jointed ones in terms of equine comfort. They presented a smooth parallel contact with the soft palate, rather than a sharp angle, and the Myler bits, which have a ‘sleeve’ over the joint, appeared to be the best of the lot. Clayton noted, however, that the length of the central link was important: too long, and it would interfere with the sides of the lower jawbone, which are considerably narrower than the upper jaw.
Interestingly, comparisons of the fluoroscopes taken with and without rein tension showed that with contact, the mouthpiece of a snaffle bit moves away from the roof of the mouth presumably increasing the horse’s comfort level. However, rein pressure moved the mouth- piece closer to the pre-molars, which could conceivably cause an interference problem with some horses. All of the bits also put pressure on the tongue and the ridges of the upper palate.
These initial findings provide a much clearer picture of what goes on in that dark cavity when a bit is thrust into the mix · but the second phase of the study reveals a number of intriguing compensatory behaviours horses exhibit when bridled.
Fluoroscopy revealed that while the horses stood quietly with the bits resting on their tongues between 60 and 80% of the time, the rest of their time was spent chewing, with their mouths open, or grasp- ing the bit between their cheek teeth. All of this could have been observed without the benefit of a fluoroscope, of course but
the radiographic images revealed a hidden behaviour, too. Fully 50% of the horses filmed repeatedly tried to get their tongues over the bit, folding the tongue double so that a portion of it billowed over the bit’s mouthpiece. Clayton postulated that the action, which occurred several times over the course of a 20-second fluoroscopy, was an attempt to provide a cushion between the joint(s) of the bit and the soft palate on the roof of the mouth.
When tension was taken up on the reins, all of the horses’ mouths became much more active, gaping open for seconds at a time, leaning against the bit (another behaviour which seemed to move the bit’s central joint or joints away from the palate, instead indenting the tongue), chewing, grabbing the bit mouthpiece or rings between the cheek teeth, or billowing the tongue. “We believe that horses develop these behaviours to help relieve pressure on the palate,” said Clayton.
Does wearing a bit affect the swallow reflex? Clayton examined this issue by rigging up several horses with an endoscope threaded from the right nostril down to the pharynx. Each horse was asked to gallop for one minute on a tread- mill, while a tube in the endoscope infused water into the horse’s throat at a constant rate of five millilitres per minute, to stimulate the swallow reflex. To serve as a control, some of the horses wore only halters, while others wore bitless bridles, or single- or double-jointed snaffles.
Using the endoscopic camera, Clayton and Fred Derksen, DVM, an endoscopic specialist, counted the number of swallows each horse took and charted the average per minute. In general, they found that the horses wearing bits swallowed less than those in halters or bitless bridles. Simulated tension on the reins seemed to restrict swallowing even more. But whether a reduced frequency of swallow- ing affects athletic performance isn’t clear and will probably require further study.
Clayton did come to several other conclusions, however, as a result of her investigations. For example, she discovered that some horses have bars shaped like a wide, flat shelf, while in others, the jawbone is almost triangular in shape, creating a much narrower and less accommodating bearing surface for the mouthpiece. In males, the canine teeth can sometimes interfere with the action of the bit, and need to be floated. There’s also a considerable amount of variation in the shape of the equine palate. Those which are arched can better accommodate the flex of a jointed bit, while horses with flatter palates might be happier in a straight-bar snaffle.
Finally, Clayton noted the presence in some horses of bone spurs on the bars of the test horses’ mouths possibly as a result of years of harsh bit action there. “They’re not all that uncommon, and horses who have them are generally pretty resistant,” she says. Surgical removal might be the only solution.
All of this serves to confirm something that most horsepeople already know: that choosing the right bit for each horse is a combination of assessment, measurement and a whole lot of trial and error.