October 2000

Building Strong Bone

by LEIGH ANN HOWARD

This is the time of year when our attention turns to the yearlings. Our hopes and dreams for future racing stars. If we are going to get to the races by next summer we should have been "breaking" our early youngsters by now. 

As far as the "breaking" process goes, I would hope that each young horse is started by a handler who understands that the goal is to have our horse reach the races with sound legs, sound mind and a willing attitude. The horse certainly needs to have good manners but should not be so disciplined as to be submissive and cowering.

The young horse should, of course, know how to balance a rider, go forward, stop, turn both directions and back up without fear. He should also load in a trailer, pick up all four feet on command, know how to lead, be groomed and bathed and just generally handled. All of these things are very basic and also very necessary. The young horse will eventually have a second career, either in the breeding shed or in a riding stable, so a good foundation is paramount.

So, in the best interest of your horse, see that the foundation training your horse receives is the best that is available. Don't cut corners; your horse's entire life will be affected by this early training.

This breaking period usually commences when the young horse is nineteen to twenty months old. In other words, if he were foaled in February, the "breaking" process starts in August or September. Thirty to sixty days is spent on the farm and at a training track. After that time the young horse is, normally, turned back out with his or her pasture mates to contemplate the future! 

The youngster is probably left out in pasture until December. At this point serious training is started. Because it is always costly to lose time with respiratory infection, it is wise to vaccinate the yearling with Flu/Rhino twice during a 45-day interval before starting this serious training.

Training and developing the young racehorse requires, among other things, regular intervals of "stress and recovery". All tissues in an athlete's body respond to stress by strengthening the stressed areas. The job of the trainer is to see that the horse is stressed gradually in order to stimulate the building of dense bone and stronger connective tissues. If the horse goes slightly beyond the point of positive stress then the systems actually break down.

A very good example of this is the "bucked shins" syndrome. Young horses start out with round cannon bones. That is, if you take a cross section look of an untrained horse's cannon bone, you would see that the bone is of equal thickness all around. This same horse, after six or eight months of proper race training, would have a cannon bone with much more thickness of bone on the front. This is because the body has reacted to the stress of training by making the stressed area (front of the cannon bone) stronger. The body has created and laid down many layers of new bone.

The horse is said to have "bucked his shins" when the amount of stress to the front of the cannon bone has been more than the new bone formation could handle and it simply breaks down. At that point the horse is sore to the touch and often sore to walk and the trainer has to back off and start over again.

The body only strengthens when it is stimulated to do so. This means that if the horse becomes sick or is injured to the point that all training activity stops, the strengthening or laying down of new bone also stops. This is why most recommendations call for reduced activity rather than NO activity when a training set-back occurs. In the case of a respiratory infection, when activity MUST stop, as soon as the horse is able to return to training then the training must start at a very much reduced level and build back up again.

So, how do we go about stimulating the young horse just enough to build a strong body, without going too far and breaking him down? I'm sure there have been many different training regimens used by trainers through the ages, all designed to build denser bones and stronger athletes. The one I'm most familiar with is called the Maryland Shin Program. Developed at Fair Hill Training Center in Fair Hill, Maryland, by Dr. David Nunamaker and Dr. John Fisher, this program is touted to be the best method to eliminate or reduce bucked shins. Dr. Nunamaker is an equine orthopedic surgeon at the University of Pennsylvania's New Bolton Center. And Dr. Fisher is an equine veterinarian and trainer based at that training center.
Dr. Nunamaker and Dr Fisher discovered that the cannon bone needs to be stressed at certain intervals and at certain speeds in order to properly stimulate the cannon bone, at a progressive but gradual rate.

Here is an excerpt out of the 1994 The Thoroughbred of California article "The Buck Stops Here" by Silvia Bachmann, describing how these two doctors developed this program: 

'In a 1991 interview in The BloodHorse, Dr. Fisher proclaimed that he no longer has any horses with bucked shins - period. Today (1994) he has backed off a bit from that statement, though he holds firm in his conviction that this program is the best method for training young horses.'

"There is absolutely no question in my mind that this is the proper way to handle bone growth in young horses," said Fisher. "It's not a guarantee that every horse won't buck his shins because there's an exception to every medical rule. So I'm sure there are horses out there that for other extenuating circumstances will make their bone much more subjective to bucking and won't remodel properly. But by and large, all horses need this kind of work in order to remodel."

'It is estimated that anywhere from 65 to 90 percent of all two-year-olds buck their shins. According to research by Nunamaker, approximately 12 percent of horses that shin buck go on the develop saucer fractures. Eliminating the first problem can help to eliminate the second. "We just don't have many injuries at all," said Fisher. "No more tendons, no more suspensories, no more fractures."
'With traditional training methods, where horses undergo long, slow gallops with works every seven to 14 days, the bones are signaled to remodel for training, while horses that breeze more often remodel their bones for racing.'

'When a horse is breezed, the bone faces what it sees as an emergency, high-stress situation and begins immediately laying down new bone. This new bone is weak and needs to be strengthened through later remodeling, which would be triggered by further breezes spaced closer together. If remodeling is not allowed to take place and the horse is asked to do too much before he is ready, the new bone will be weak and prone to injury. The bone-strengthening is entirely based on stress and recovery to gradually increase bone density and strength.'

"We took three yearlings one time and just turned them out in the field from September to June," said Fisher. "Then we took three more horses and broke them, trained them, and got them up to galloping. We galloped them for four months, two miles a day, maybe 18-second furlong, but no works. When we examined the bone on all six horses, there was no difference. The horses that did all those two mile gallops - great for the heart, great for the muscle, great for the mind - didn't do a thing for the bone. The bone never got the message."

"Then we took three more," he continued, "and we worked those horses a lot - three days a week. Now I sure don't recommend it because when you get to a half-mile and more, three days a week, it's incredible. You just don't do that to horses, but we did it to see what would happen to the bone. And when we examined the bone on those horses, they were equivalent to four-year-old racehorses. So it was clearly the speed that had changed the bone."

'The idea was to discover the correct amount of work needed to trigger the bone to remodel while at the same time not injure the horse or disturb him mentally. Fisher and Nunamaker have modified the program several times since its inception. Fisher hopes to one day have the program published much like a recipe in a cookbook.'

'The proponents of the program say it benefits older horses as well and should not be limited to juveniles. The program can be undertaken with horses that have been properly broken and are able to gallop one mile comfortably. Over a 16-week period, horses gradually transition from a one furlong work at 15 seconds to a half-mile or more work in 13 second furlongs.'

Many California trainers have adapted Doctors Nunamaker and Fishers' Maryland Shin Program to fit their own facilities and situations. Most are on training tracks rather than the racing tracks, since this method takes completely different instruction from the trainer and riders that understand the concept. The racetrack style of 'galloping out' after the work, or a horse that gets caught in traffic and is trapped in an unplanned work, can completely ruin a well planned shin program.
Dr. Jack Woolsey, from Santa Rosa, was quoted extensively in Silvia Bachmann's article and his chart of the Maryland Shin Program follows.

Steve Charles, trainer at Lakeview Farm, is a strong proponent of the program. He has this to say about the extra time needed to complete this program. "If the owners would look at this as an overall program, they'd see that when these horses are done with this program, the chances of them being laid up with buck shins are so slim. It's a cost savings. They won't have to spend all that time and money while their horses are laid up and getting them back to where they were before they shin-bucked. It's worth the extra time. Also I think it develops the horse, mentally, a little bit better than the traditional method."

None of the people using this method of training seem to have any problems with their horses mentally or with their attitudes. In fact, just the opposite seems to be true. Dr. Fisher says he has some of the best mannered horses around. I know that when the jockeys I use come back after the first race on one of my horses the very first comment is about how well mannered and tractable the young horse was during the race.

Most of the trainers using the program vary it slightly but all do each distance, at each speed, four times before moving on to the next distance and speed. There is never more than four days between the shorter distance works. This is because Nunamker and Fisher found that the new bone will stop remodeling, and, in fact, weaken, with no additional stress after five days.

Once the program is completed the horse starts conventional training. By this time there should be enough bone strength that the risk of shin bucking is past. The only situations that could affect that risk factor might be a radical change in track surfaces or track circumferences. For instance, if the program has been undertaken on a half-mile track and the horse is switched to a mile track, that could make a difference.

So, when a trainer adopts this program it is going to take longer to get the horse to the races. Maybe even two to three months longer. But, if your horse bucks his shins he will be out for at least that long, maybe even longer. And then he has to start all over again. 

So which program costs more money?

Copyright © 1998-2000 California Thoroughbred Breeders Association