BLACKSBURG, Va. – America’s growing obesity problem has alarmed physicians and public health officials, and veterinarians have recently focused attention on fat dogs and cats.
Now, a team of researchers in the Virginia-Maryland Regional College of Veterinary Medicine and the College of Agriculture and Life Sciences at Virginia Tech has determined that horses are also facing serious health risks because of obesity.
Fifty-one percent of the horses evaluated during the pioneering study were determined to be overweight or obese – and may be subject to serious health problems like laminitis and hyperinsulinemia.
Culprits. And just like people, it appears as though the culprits are overeating and lack of exercise.
This extremely important problem has been under-reported, said Craig Thatcher, a professor in the veterinary college’s Department of Large Animal Clinical Sciences and Diplomate in the American College of Veterinary Nutrition.
Thatcher and his colleagues believe the study results suggest horse owners should change some of the ways in which they care for their horses.
“Obesity, over the past decade, has become a major health concern in horses,” said Scott Pleasant, an associate professor in Department of Large Animal Clinical Sciences and Diplomate in the American College of Veterinary Surgeons.
“This is primarily because of its association with problems such as insulin resistance and laminitis.”
Laminitis. In fact, it was a spike in pasture-associated laminitis cases that led Pleasant to grow curious and seek the collaboration of Thatcher, an internationally renowned veterinary nutritionist, on the innovative research project.
“Laminitis is a failure of the connective tissue bond between the horse’s hoof and the bone within the hoof,” explained Pleasant.
“When that bond fails, and the hoof and bone start to fall apart, it is extremely painful to the horse,” he continued.
The study hypothesized that overweight horses may suffer from insulin and sugar imbalances, chronic inflammation and oxidative stress, a malady that occurs as a result of changes to metabolic processes that alter the delicate balances between the destruction and creation of new cells in the body.
Problems. Other problems caused by equine obesity are heat stress, increased bone, tendon, and joint injuries and reduced performance levels.
Until now, only one other study had looked at obesity in horses.
A 1998 owner-reported survey of horse owners conducted by the USDA’s National Animal Health Monitoring System suggested about 5 percent of horses were overweight.
Based upon the horses routinely seen through clinical practice in the Veterinary Teaching Hospital, however, the researchers suspected the incidence might be higher.
“We thought it was at a level of at least 15 percent,” said Thatcher.
The research team has already made some alarming discoveries. Fifty-one percent of the horses in the study were found to be overweight and 19 percent were found to be obese.
Eighteen percent of the overweight horses and 32 percent of the obese horses were hyperinsulemic.
The study also suggests equine obesity may result from natural grazing behavior instead of the overfeeding of grains and other feed supplements, which defies conventional thinking on equine weight matters.
The majority of horses examined in the study were fed primarily pasture and hay with very little grain and concentrate.
Instead of overfeeding of grain and concentrates, the evidence indicates improved forage and lack of exercise are the two most common contributing factors in equine obesity.
Management. Horses today are managed much differently from their evolutionary roots, indicated Pleasant.
“The horse evolved as a free-roaming grazer on sparse pasture types,” he said.
Later the horse served primarily as a work animal, serving as a source of transportation and draft power. Today, most horses serve as companions and light performance animals, he said.
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