Equine Metabolic Syndrome

by Tori Jordan BA VetMB MRCVS

Out of every ten cases of laminitis, recent research has indicated that nine of these may be caused by hormonal problems, such as Cushing’s disease and equine metabolic syndrome (EMS).ems 1

So what is EMS?

The term ‘equine metabolic syndrome’ refers to a collection of risk factors which indicate an increased risk of laminitis. The main risk factors involved include obesity, which is often overlooked or ignored by horse owners, and insulin resistance.

What is insulin resistance?

Insulin is an important hormone in sugar metabolism. When it is produced, it signals to the body to store sugars absorbed from the gut and to synthesise fat. With insulin resistance, this mechanism is unable to function normally. The body is still producing insulin but the cells are not responding to it. So, instead of the sugars being stored, they remain in the circulation. Insulin resistance actually offers a survival benefit to ponies living in harsh conditions, providing much needed energy when food is sparse. Many of the native UK pony breeds have evolved with this mechanism in place as, in the wild, it would have saved them from starvation during the cold winter period. However, now that we have domesticated these breeds, and are providing them with high quality food all year round, this once beneficial adaptation has become detrimental to them, predisposing them to EMS and laminitis.ems 2

How can I tell if my pony has EMS?

EMS is most common in middle-aged pony breeds, particularly those who are overweight or obese. Often, these ponies are seen as ‘good-doers’ who seem to put on weight at the drop of a hat. Ponies with EMS often have abnormal fat deposits, which can be found along the top line of the neck, behind the shoulder and on each side of the tail head. As mentioned above, this condition is also strongly associated with laminitis and this may be the first clue that your pony is affected. EMS is tricky to diagnose, and your vet may need to perform a variety of tests to help diagnose it. A common starting point is to measure insulin levels in the blood. When the cells in the body become insulin resistant, the body reacts by producing more and more insulin, in an attempt to make the cells respond. As a result, many ponies with EMS have high insulin levels in their circulation. In some cases, however, the insulin level can still be normal and your vet may need to perform additional tests to assess your horse’s ability to metabolise sugars.

ems 3What do I do if my pony has EMS?

Once EMS is diagnosed, the aim of treatment is to make the cells sensitive to insulin again, reducing insulin levels in the blood and, ultimately, reducing the risk of laminitis. The two main ways of achieving these aims are regular exercise and returning your horse or pony to their ideal weight. Exercise not only aids weight loss but also increases insulin sensitivity. Once laminitic feet are sound, your horse or pony’s exercise programme should be gradually increased to include at least 3-4 sessions per week. If you are unsure whether your pony needs to lose weight, or want some advice on how to go about putting him on a diet, contact your vet for help. While it may seem unfair to him at first, placing your pony on a zero-grazing diet means that you have complete control over what and how much he eats! To get him to lose weight, you should feed just 1.5% of his ideal bodyweight each day (i.e. if he weighs 350kg but should be 300kg, feed 4.5kg of hay each day). Ideally, he should be fed only mature, grassy hay together with a vitamin and mineral balancer. Soaking hay for at least an hour before feeding will help to remove a large proportion of sugar from it, reducing the calorie content significantly. You can monitor your pony’s progress at home with a weigh tape to ensure things are moving in the right direction! Sometimes, weight loss and exercise are not enough to improve insulin resistance. In these cases, your vet may suggest a drug called metformin, which reduces the amount of sugar that ponies can absorb from the gut into the bloodstream. Metformin, however, is not a quick fix and should not be used as a replacement for exercise and weight loss! Confused?! Don’t worry! EMS is a complex condition and the research relating to it is far from finished!

If you have any questions or queries, contact your local vet for more information. If you have any questions about any aspects of your horses’s health, or indeed your pet, farm or smallholding animals, please do not hesitate to contact us on 01892 835456. Putlands Veterinary Surgery is based in Paddock Wood in Kent, and offers a friendly, professional and personal service for all species of animal. We have four dedicated large animal vets with a wealth of equine experience between us, and are always happy to help.

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