Page 158 - February_2023

VETERINARY VIEWS
PROTECTING BONES AND JOINTS
One adaptable system in development is the “organ” of bone, and another is that of the joints. Data indicates that unrestricted turnout exercise
for 24-7 results in better bone density and reduced developmental orthopedic disease (DOD). A young horse confined to a stall does not develop the bone density of a youngster that is given the opportunity to exercise. Restriction of exercise retards normal development of the joints, creating a longer opportunity and greater risk to incur DOD.
A concept known as enhanced cyclic loading stimulates improved structural stability of joint cartilage and bone. This is achieved with moderate exercise and is important to a young horse to develop joints and other musculoskeletal structures with optimal longevity. An excess of exercise demand damages the tissues, whereas too little exercise limits adaptation and conditioning that could enable a horse to perform well in later years.
Studies have demonstrated that a very short duration of sprint activity is advantageous to stimulate mineral deposition for optimal bone density and strength, and to elicit protective remodeling of the joint tissues. Short periods of impact loading, as with trot on a hard surface, are able to stimulate improved bone condition with an increase in mass and density, particularly in the long bones of the skeleton. For most performance and pleasure pursuits, a horse’s skeleton can be adapted by the work of trotting on a firm surface for short periods, or with sprint gallops in turnout.
A gallop for less than 1/4 mile (400 meters) is all that is needed to stimulate such an adaptive response for a racehorse. To avoid soft tissue or joint injury, the young horse is only urged to faster speed after he has been conditioned with long, slow distance work for several months.
Too much high-intensity impact can backfire, and instead of achieving adaptation, can lead to joint deterioration. Bone that overlies cartilage in the joint may adapt initially, but too much stimulus overly increases cartilage mass and stiffness, thereby losing some shock absorption ability. Joint cartilage incurs more impact stress, and if damaged may later develop degenerative joint disease (arthritis).
A commonsense approach of “less is more” enables you to implement short periods of impact exercise that stimulate a beneficial adaptive response in
the joints and in long bones. As efforts are made
to protect growing joints and bone, these same techniques also take care of tendons, ligaments, and muscles during their development.
An excess of exercise demand damages the tissues, whereas too little exercise limits adaptation and conditioning that could enable a horse to perform well in later years.
THE EARLY YEARS: NUTRITIONAL CONCERNS
Growth is a lengthy process in a young horse, taking a couple of years for the skeletal structures to lengthen and mineralize. During that time, attention should be paid to the details of a growing horse’s nutritional plane: Feed as little concentrate supplement as necessary to maintain good, but
not obese, body condition and growth rates. Some breeds thrive on 70 – 80 percent of what might be necessary for “hotter” breeds like Thoroughbreds.
Too much consumed energy contributes to developmental orthopedic disease (DOD) problems that adversely impact athletic longevity. Overfeeding of carbohydrate energy sources, such as grains, starches, or high fructans or sugar feed is a primary cause of DOD, particularly during certain phases of growth. These forms of feed, particularly in the face of mineral imbalances, lead to abnormal and improper mineralization of bone; then, legs are prone to developing defects. High protein is not the initiating problem, although a young, growing horse doesn’t need more than 12 – 14 % protein in the ration.
A practical feeding to promote musculoskeletal health in a young horse can include free choice hay.
A diet must be balanced to achieve musculoskeletal health, and malnutrition (either underfeeding or overfeeding) should be avoided. Underfeeding may stunt a growing horse and if minerals are lacking, can still cause DOD. Overfeeding, especially carbohydrate- rich grains and supplements that contribute excess calories, potentially leads to permanent limb damage along with metabolic and hormonal upset resulting in DOD.
The metabolism of a young horse is especially impacted by the tendency of horse owners to feed as a matter of convenience rather than focusing on evolutionary adaptations of the equine digestive tract. Wild horses evolved to eat small amounts frequently throughout the day,
with seasonal periods of relatively poor nutritional availability. The current state of domesticity of
the horse finds owners continually offering grain and high-carbohydrate feeds year-round, coupled with exercise restriction and twice a day feeding. Studies document that horses left to their own devices do not voluntarily fast for more than 3 - 4 hours, even at night. Barn practices of feeding twice daily portions of restricted hay and copious grain means that each meal is consumed within a couple of hours and then the horse goes for long periods of fasting before the next meal arrives. This results in huge peaks and valleys of insulin and other hormones that exacerbate the potential for development of DOD; fasting also contributes to formation of gastric ulcers.
Practical feeding to promote musculoskeletal health in a young horse includes:
• Free choice grass hay
• Feed appropriate calcium/phosphorus
ratios designed for growth
• Ensure micromineral (selenium, copper,
zinc, and magnesium) balancing of the ration
relevant to your specific geographic location • Minimize or eliminate carbohydrate-rich
feeds like grains or similar supplements • Offer high fat foods (oil, rice bran) to
substitute for needed calories
• Refrain from overfeeding excess protein
Consult with your veterinarian to individualize an optimal diet tailored for your young horse relevant to his genetic tendencies, growth spurts, and athletic pursuits.
156 SPEEDHORSE February 2023
Overfeeding of carbohydrate energy sources, such as grains, starches, or high fructans or sugar feed is a primary cause of DOD, particularly during certain phases of growth.
Common Locations For Developmental
Orthopedic Disorders (DOD) In The Young Growning Horse
A horse’s skeleton can be adapted by the work of trotting on a firm surface for short periods, or with sprint gallops in turnout. A gallop for less than 1/4 mile (400 meters) is all that is needed to stimulate such an adaptive response for a racehorse.