Overweight horse? Obesity Management in Horses

Do you have an overweight horse? Here Sue Dyson, Head of Clinical Orthopaedics at the Animal Health Trust Equine Clinic, takes a look at how we can manage obesity in horses.

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Obesity in horses

Obesity is an excess of body fat accumulation which has a potentially negative impact on health. There are numerous consequences of obesity, including reduced efficiency of athletic function. Premature fatigue can predispose to musculoskeletal injury. Overload of joints can predispose to injury. Increased load on limbs is particularly relevant in horses with musculoskeletal injury and we know that approximately 47% of the so-called normal sports population is lame.

Obesity results in reduced heat tolerance because fat acts as an insulator and obesity results in decreased efficiency of heat loss. Overheating reduces performance.

Equine Metabolic Syndrome (EMS)

Obesity may result in the development of equine metabolic syndrome (EMS) , a condition which has similarities to Diabetes type II in overweight people, with altered sensitivity to insulin. Typically affected horses have a cresty-neck appearance and obvious fat deposits. Equine metabolic syndrome results in a predisposition for laminitis, including ‘atypical’ laminitis.

Obesity has also been associated with laminitis, most particularly in native pony breeds kept at grass.

We do not see obese racehorses, elite endurance horses, elite event horses or professional polo ponies. These horses are worked and fed appropriately, in contrast to many show horses, dressage horses and general purpose riding horses. Recent data suggests that the prevalence of obesity is getting worse.

The 2015 National Equine Health Survey was conducted by the Blue Cross and the British Equine Veterinary Association and a questionnaire survey data from 4951 ‘keepers’ of 14,952 horses was analysed. Approximately 23% of horses were ‘overweight’ compared with 17% in 2014 and 8% in 2013.

Understanding Obesity

Obesity or a fat horse, results in an increase in body weight and is manifest as a high body condition score. The body condition score is a method of quantifying a horse’s overall condition. This, essentially reflects how easy it is to detect bony landmarks by visual inspection and palpation and the identification of fat deposits. Such fat deposits are sometimes confused as abnormal swellings reflecting muscle injury, despite usually being bilaterally symmetrical. An example of this is just behind the shoulder blade or above the tail head.

There are a number of factors influencing obesity, including food energy intake and energy expenditure associated with both physical activity and thermoregulation (heat control). There is probably also a genetic component. It is very simple. If energy consumed as food exceeds energy output through exercise and heat control an animal will gain weight.

To reduce the prevalence of obesity education of owners, trainers and judges is essential. In particular riders, producers and judges of show horse classes must be made aware of the potential long-term adverse consequences of obesity. Fat horses should not be allowed to win show classes.

What we can do to manage an obese horse?

Food intake should match energy output. Therefore food requirements are based on energy demands. There should be no ad libitum feeding of a fat horse. Horses do not need access to food all the time. The concept of feeding little and often is fine, provided that the total amount of food offered is regulated and is appropriate for the horse’s level of work. If a horse is overweight its energy input must be reduced, and therefore the food intake must be cut back.

> All food stuffs should be weighed.

> Hay should be soaked for approximately 4 hours, because this reduces the amount of soluble carbohydrates available. Ideally the hay should be fed in small-holed double hay nets to reduce the speed of consumption.

> If the horse has access to pasture the grass should be mown and consideration given to limited strip grazing.

> Horses should be fed minimal concentrate feed, no supplements/ treats, other than a balancer to insure correct vitamin and mineral and protein levels.

> Horses should not be rugged, unless the weather conditions are appalling, because rugging reduces heat loss and therefore energy expenditure.

Remove the droppings from the field if not daily, regularly, a good way to monitor input and output. Cut the grass in the paddocks regularly.

> Exercise is crucial because exercise reduce fat mass and thus increases increased insulin sensitivity which can reduce risk of obesity. Exercise should be sufficiently vigorous to raise the horse’s heart and respiratory rates and should be for as long as possible. Horse are not designed to be sedentary animals.

Get on top of vital information

The horse’s body weight should be established at the outset and should be monitored weekly. Weight tapes are not particularly accurate, but do provide a means of objective assessment. A weekly target of bodyweight loss for your fat horse should be aimed for. Monitoring of body mass index or body condition scoring provide some reasonably reliable information about obesity. Your veterinary surgeon should be able to advise you how to do this.

At the start of a diet the current weight of your fat horse should be estimated (for example, 520 kg) and a target weight determined (for example, 490 kg). Thus the horse needs to lose 30kg bodyweight, aiming to see between 5 and 10kg weight loss a week. Once a horse starts to lose weight, the diet should still be continued until the target weight is achieved. The horse’s shape will change and saddle fit may need to be reassessed. Once the target weight is reached it may be acceptable to increase food intake again slightly, to meet maintenance requirements.

Remember: It’s just as important to keep on top of your horse’s body weight whether they appear ‘fat’ or not. Regular condition scoring, weigh taping and overall review of your horse’s health should be a part of your routine care.