The Dangers of Equine Obesity
By Margaret Evans
When I bought my Anglo-Arab mare, Fari, back in 1999, she was a somewhat tubby, opinionated three-year-old. I needed to get weight off her and keep it off, but it was a real challenge living on our farm in a sea of grass. Controlled grazing and measured feeding was the start of a lifelong management program that ultimately shed over 200 pounds off her frame. But tragically it wasn’t enough.
After several incidents with laminitis that also triggered excruciating abscesses, she was diagnosed with equine metabolic syndrome. She was permanently on medication, lived her life in heart bar shoes, and was constantly being measured for weight loss or gain. During the good years she could be ridden for pleasure, but my hopes of riding her in distance competitions were permanently dashed. But I adored her for whatever the good times gave to us until, at age 13, one final, tragic bout of laminitis took her from us.
The issues that plagued Fari are far more common than one might think. According to research over the past six years, at least one in five and potentially one in two pleasure horses are overweight or obese, leading to conditions such as laminitis, equine metabolic syndrome, chronic inflammation, arthritis, heart issues, heat stress, and bone, tendon, and joint problems.
Earlier this year a pilot study carried out by the UK’s University of Nottingham’s School of Veterinary Medicine and Science found that obesity rates among horses are as high as those among humans. From a questionnaire survey, they found that at least one in five horses ranged from overweight to obese.
According to the University’s press release, the study assessed the incidence of obesity among horses whose owners were clients of a veterinary hospital associated with the school. The research was supervised by Dr. Sarah Freeman, a specialist in veterinary surgery, and the study was done by third year veterinary student Helen Stephenson.
Five hundred owners were sent the questionnaire and 160 responded. They answered questions about their horse’s condition and their feed regimen. Owners were asked to score their horse’s weight on a scale of one to five, with anything over three being overweight. As for feed, grass was the main forage for half the horses and coarse mix was the main source of concentrate feed. Only one in ten horses was not fed a form of concentrate.
The researchers then assessed 15 randomly selected horses to compare their own scores with the estimations of the owners. When the research team did the appropriate measuring for height, length, and girth, eight of the owners had underestimated weight.
A significant number of horse owners underestimate their horse’s weight. A recent study estimates that the prevalence of overweight and obese horses could be as high as 54 percent.
On the basis of their findings, the researchers estimate that the true prevalence of overweight and obese horses could be as high as 54 percent compared to the 20 percent shown from the questionnaire results.
The results of the study dovetail with previous work done in the United States, where veterinary scientists have noticed the parallels in health threats between obese horses and humans. “There is a striking parallelism between humans and horses when it comes to obesity,” said Philip Johnson, professor of veterinary medicine and surgery at the University of Missouri-Columbia in a press release. “Some of the very same problems humans encounter with obesity may also occur in horses.”
Compared to other health conditions in horses, obesity has been studied less, but in the past few years it has become clear that horses face the same human health complications. It may be time to reconsider the importance of further research into horses’ weight, weight gain, the content of feed being given and in what proportions, as well as the role exercise plays in weight control.
In another independent study, a team of researchers in the Virginia-Maryland Regional College of Veterinary Medicine and the College of Agriculture and Life Sciences at Virginia Tech investigated the serious health risks associated with equine obesity. During their research in 2006, they studied 300 horses between the ages of four and 20 years old from 114 farms. Body conditioning scores (BCS) were assessed on a scale of 1 to 9 with 8 or 9 signifying obesity and 1 being emaciated.
Measurements were based on girth circumference, neck circumference, body length, and height.
Data was collected between 6 a.m. and 12 noon, before any of the horses were fed grain or concentrates which could alter glucose or insulin levels. Blood tests were taken and owners were given a questionnaire.
They found that 51 percent of the horses had a BCS of over 6. Thirty-two percent were over 6 but under 8, and 19 percent were in the 8 to 9 range. Thirty-two per cent of the horses with a BCS of 8 to 9 were hyperinsulinemic (elevated level of insulin).
The interesting aspect of this study was that the majority of these horses were pasture fed or fed on hay with hardly any grain or concentrates. Since these were farm raised horses, the researchers theorized that they were pastured on enriched forage primarily used for fattening cattle and other food animals. When rich food is coupled with no exercise, weight gain sets in.
A conditioning program will stave off obesity and improve overall health.
The tendency to overfeed horses can occur because it is easy to overlook the fact that the genetics of horses, like their wild counterparts and many other species, allows for the extra storage of fat in the fall in preparation for winter when less food or poorer quality food is available. In nature, horses would typically lose weight over winter and regain it in spring. But in their domestic world, horses are fed year round and never lose those extra pounds.
There’s also a social perspective. While obesity in people is recognized as being a health issue, the researchers noted that many horse owners prefer to see their animals looking well fed. The issue of health consequences to horses does not seem to be as acute as the same health concerns for people.
The counter action to obesity, before life threatening problems set in, is meaningful exercise that raises cardiovascular rates and stimulates fat burning. From an equine health point of view, a year-round conditioning program, alongside a feeding regimen approved by a vet, should be in play with some allowance for winter weather conditions.
Main article photo: Obesity can lead to laminitis, equine metabolic syndrome, chronic inflammation, arthritis, heart issues, heat stress, and bone, tendon, and joint problems.
This article originally appeared in the August 2011 issue of Canadian Horse Journal.