CirCling BACK

Joint injuries, lameness, and joint disease, such as osteoarthritis, remain among the most important causes of lost training days, decreased performance, and early retirement from competition.

Most horse owners know that they can’t take an idle horse out of the paddock and have it negotiate a course of show jumps, or complete an all-day trail ride without a period of conditioning. Those who try to short-cut the necessary buildup of fitness often end up with horses that are sour at best and lame at worst. To get the best results and avoid the possibility of serious injuries, horses should be trained in a program that asks for gradual improvement, guided by the specific fitness response of each horse.

The training must overload the current level of fitness. This means that the trainer must ask the horse to do more work than it is used to doing, in order to increase ability. This overload must be significant enough to produce an effect in which the body responds by building muscle strength, increasing cardiovascular fitness, and augmenting respiratory efficiency.

Another principle of training is that the workload must continue to increase as fitness is built. As the horse reaches better condition, the exercise must be made more difficult or be carried out faster or for a longer period of time.

Training should also be specific to the discipline toward which the horse is being pointed. While the earliest training steps might be the same for horses in all disciplines, eventually jumpers, endurance horses and barrel-racing mounts will be asked to perform different types of exercise in their training regimen. This specific conditioning will allow horses to gain strength and agility in ways that are most helpful for their particular performance demands.

WOrKING ON THE CIrCLE

Regardless of discipline, young horses in training frequently work in circles, either on lunge or long lines, under saddle, or in round yards. During these exercises, horses typically lean into the centre of the circle to maintain balance. As a result, the strains placed on the inside limbs are different from those withstood by the outside limbs.

Protecting equine joints starts early in life by ensuring a balanced diet, adequate weight-bearing exercise, and minimal musculoskeletal trauma. Offering joint supplements prior to injury also helps protect joints, and feeding those same supplements in the face of wear and tear or injury can also help slow the progression of osteoarthritis.

“Osteoarthritis is a leading cause of lameness and loss of function in athletic horses. Currently, there is no cure for osteoarthritis. While many treatment options exist, no technique effectively returns damaged cartilage to its original state. Instead, owners and veterinarians manage discomfort with symptommodifying drugs, such as corticosteroids and anti-inflammatories, and oral joint health supplements,” said Katie Young, Ph.D., a nutritionist for Kentucky Equine Research.

Considering how commonly young horses are asked to work in circles, researchers recently examined whether this type of exercise leads to asymmetry of the forelimbs. In addition, markers of cartilage metabolism were also assessed.

Calves have been used in previous studies as skeletal models of juvenile horses, so this study used 24 nine-week-old calves. Calves were exercised in small 12-metre circles, larger 20-metre circles, or on a straight line on a treadmill. The calves ambulated slowly, walking at a rate of only 1.1-1.5 metres/second, starting at five minutes per day and increasing five minutes weekly until reaching 30 minutes per day over the seven-week study.

After 49 days the forelegs of the calves were subjected to computed tomography (CT). These scans revealed that the outside forelegs had a greater diameter than the inside forelegs when the calves were walked in small circles.

“This increased diameter represents bone adaptation to stress placed on the limbs while exercising in a circle. The difference in diameters supports the theory that exercising in small circles results in uneven stresses on the inside versus outside of the limbs,” explained Katie.

In addition, the veterinary research team found an increased level of metabolism, or turnover, in cartilage harvested from the outside

“Therefore, even at slow speeds, circular exercise can negatively affect bone and joint health. These changes may be even more pronounced at higher speeds and workloads, such as those experienced by young horses in training,” Katie said.

These findings suggest that frequent circular exercise of young horses may lead to bone and joint abnormalities that can affect the horse’s long-term health and soundness.

These data may also prompt additional research into the best type of work for training horses.