When more than 50,000 people cheered Zenyatta to victory in the 2009 Breeders' Cup Classic, they were responding to the mare's personality and charisma as well as the sheer athletic prowess with which she defeated rivals repeatedly.
Racehorses require an incredible level of fitness and soundness to run all out against their competition. The best of them, like Zenyatta, possess a combination of natural ability and the courage and desire to win.
Just like any athletic horse, a racehorse requires proper feeding, management, and training to perform well. The most successful trainers have learned how to bring a racehorse to its peak and detect very minor health issues before they flare into major problems.
Thoroughbred trainer John Shirreffs and Quarter Horse trainer Paul Jones recently discussed how they manage the horses in their care. Shirreffs trained Zenyatta, won the 2005 Kentucky Derby with Giacomo, and has conditioned such other major winners as Tiago, Life Is Sweet, and After Market. Jones, the all-time leading Quarter Horse trainer by earnings and 10-time national champion, has won the All American Futurity three times.
Theoretically any breed of horse can compete in most equine disciplines, but rules limit the breeds that can race. Thoroughbreds go long, usually from six furlongs to 1 ¼ miles, and Quarter Horses go short, primarily 300-440 yards up to 870 yards. The two breeds are designed for their respective distances, with Quarter Horses short-coupled and able to reach high speeds very quickly, and leggier, lankier Thoroughbreds built to sustain their speed over more ground.
Shirreffs and Jones pay almost as much attention to their charges' mental states as to their physical condition. "I think kindness is the big key to horses," says Shirreffs. "I always ask the exercise riders, grooms, and hot-walkers to talk to them. Horses are always trying to learn from their environment."
Zenyatta, for instance, seemed to thrive on the attention she received during her years at Shirreffs' barn. And like most horses, she also seemed to enjoy having a daily routine. "They're creatures of habit," says Jones, "so you want everything to be a good, positive experience for them."
Jones extends this positive approach to his training techniques. For example, he takes great care in schooling a young horse in the starting gate so the athlete will learn to break out of the gate quickly and safely.
"When we're breaking them, we teach them to just walk through the gate," Jones says. "Then we teach them to walk into it and stop. We want that experience from the very first time to be as hassle-free as possible."
Once they understand the concept, racehorses typically enjoy breaking quickly out of the gate as part of their competitive natures. But recognize that these horses can become discouraged, he says, if they are put into a race against those far above their ability. "It's terrible if you keep running a horse over his head and he keeps getting beat," Sherriffs says. "It changes a horse's whole psyche. (On the other hand) you'll see a horse win a couple races, and he gets braver and gets to be a better racehorse."
Importance of Bone Remodeling
Racehorses might arrive at trainers' barns to begin their racing careers as early as January of their 2-year-old season. But not all horses develop quickly enough to race at 2--Zenyatta, for instance, didn't make her first start until late in her 3-year-old season. Jones says that whether his horses start as 3-year-olds or at 2, they still face the same developmental issues.
"Bone is an organ that responds to stress and exercise," says Rick Arthur, DVM, the equine medical director for the California Horse Racing Board. "It needs to adapt to what sort of stresses are going to be put on the bone when the horse is racing."
Arthur explains that a cross-section of a yearling's cannon bone is spherical. It becomes egg-shaped by the time the horse begins racing, he says, with the thicker part toward the front and inside because the stress to that bone has caused it to remodel and become stronger in that direction.
Bone strength is crucial because of the high speeds at which racehorses travel. Chips--called peri-articular fractures--are the most common injuries seen in racehorses, says Arthur. "These are quite amenable to arthroscopic surgery," he says.
Surgical advances have allowed veterinarians to repair condylar fractures (of the outer half of the condyle--the bottom or distal end of the cannon bone that fits into the fetlock joint) successfully. Many horses that would have been euthanized in the past now not only survive but also return to racing.
Young, growing horses can develop bucked shins, a condition in which the fronts of the cannon bones become tender and sore. "So many of the injuries we deal with are really stress-remodeling injuries," says Arthur. "A bucked shin is an overabundant response to stress. The shin was overstressed too early, which caused a pathological (disease) problem."
An ideal conditioning program allows a racehorse to develop strong bones and muscles and good cardiovascular fitness without overstressing the body. Thoroughbreds are likely to "breeze" (run near or at race speed) once a week and complete one- or two-mile gallops about four days a week, whereas Quarter Horses don't necessarily gallop every day. Jones says he might simply hand walk a horse some days.
"Basically, the horse is designed to run full speed for a little less than an eighth of a mile," says Shirreffs. "In (Thoroughbred) horse racing you're asking them to carry that speed much farther. That's why it takes so long for a horse's bones to remodel (to adjust to the increased distances)."
Arthur explains that the remodeling process includes a time when the bone actually weakens. "Bone has to be demineralized before it can be remineralized and made thicker and stronger," he says.
Good trainers understand this process intuitively, Arthur says, asking the horse to do more when the bone strengthens and backing off when the bone needs time to remodel (as evidenced by lameness, bone spurs, and changes seen on bone scans).
Shirreffs starts each day by checking feed tubs to ensure the horses have eaten all their food. "Then we check their legs to see if there are any changes, such as heat and a little filling," he says.
Recognizing even the slightest change can often help trainers head off a health or soundness problem. Arthur notes that research into racehorse breakdowns has shown that a catastrophic injuries often begin with microfractures. Catching and addressing these in their earliest stages can prevent more significant injuries.
Throughout the bone-strengthening process, ligaments and tendons that support bones also must strengthen. Arthur estimates superficial digital flexor tendon damage ends about 25% of Thoroughbreds' racing careers. Jones doesn't experience as many tendon injuries with Quarter Horses because they aren't racing over long distances. Instead he watches for fractures and chips in the fetlocks and knees, which can occur because of the concussion from the high speeds over short distances.
Any horse can damage his bones and tendons, however, due to fatigue. A good training program will condition a horse so that he doesn't become fatigued. "Horses need to train," says Shirreffs. "They're not going to get bigger, stronger, and faster standing in a pasture."
The force a racehorse places on his lower limbs also make his feet susceptible to injury. He should be shod regularly in a manner that allows the entire lower limb apparatus to work efficiently.
Susan Stover, DVM, PhD, Dipl. ACVS, of the University of California, Davis, is conducting ongoing research into how racing surfaces and horseshoes affect limb biomechanics. Her work led to the elimination of toe grabs longer than 4 mm in California Thoroughbred races.
"Traction devices, such as toe grabs, are a risk," says Arthur. "Horses' feet have to slide a little bit. If they don't slide, that energy goes right up the leg (increasing the risk for injury). If they slide, some of that energy is dissipated. The toe grab interferes with slide, and it changes the angle of the foot," also impacting how energy is transferred up the leg.
Shirreffs advocates trimming and shoeing a racehorse in such a way that the adjustments do not interfere with a horse's conformation or way of going.
Well-functioning airways and lungs are as essential to racehorses as to any athletic horse, enabling peak performance. Complicating this picture of respiratory health in all racehorse breeds is exercise-induced pulmonary hemorrhage (EIPH, commonly called bleeding), which Arthur calls a "virtually normal physiological response" to strenuous exercise.
"We also have the fact that these horses are housed in stalls (where ammonia levels are high), they eat hay, they're bedded on straw," he says. "They are very prone to small airway disease."
The horse's lung anatomy doesn't help; he has long and narrow bronchioles (the tiny airways in the lungs) that Arthur says become obstructed easily by inflammation, such as allergy-induced bronchitis.
Most owners have their racehorses vaccinated regularly against common respiratory illnesses, and trainers monitor these animals vigilantly for signs of respiratory disease. They confer with their veterinarians on proper medication and/or rest regimens if a horse does develop a problem.
How much these horses exercise each day impacts the development of their lung capacity. While the occasional fast workout can sharpen a horse's speed, regular long gallops can increase lung capacity.
Young at Heart
Because racehorses are cared for daily and generally are young, Arthur notes issues such as colic are relatively rare. "Horses (at the track) have their teeth done in a regular manner," he says. "They're dewormed and have very good parasite control (also due to management because most are not turned out to pasture where they might pick up parasites while grazing). Compared to (what veterinarians see in) the regular population, these sorts of problems are relatively unusual."
A racehorse's career is often over by ages 3 to 5, a time when other athletic horses are just getting started. Because Quarter Horses as a breed are so versatile, Jones says many racehorses not used for breeding go on to secondary athletic careers such as trail riding, roping, and barrel-racing. Many Thoroughbred ex-racehorses embark on second careers as well, often in the jumping and eventing worlds.
An ideal conditioning and racing program allows racehorses of all breeds to perform at their peak, remain sound through their racing careers, and be ready to commence a second career in another discipline.
Disclaimer: Seek the advice of a qualified veterinarian before proceeding with any diagnosis, treatment, or therapy.