Tower Equine

Veterinary Surgeons


Equine Metabolic Syndrome and Laminitis - February 2014

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Q) What is Equine Metabolic Syndrome (EMS)?

EMS is a common condition affecting overweight horses and ponies which makes them more likely to become laminitic.

Everyone knows that being too fat causes horses and ponies to get laminitis, but it is only in the last few years however that we have started to understand why. Too many fat cells don’t just add to size and weight, they also interfere with the body’s control of insulin, the hormone that helps keep blood sugar levels stable. In EMS, blood sugar and insulin levels are often high, and high blood sugar levels can result in – yes you’ve guessed it – laminitis.

Q) What are the signs of Equine Metabolic Syndrome?

The most common sufferer of EMS is an overweight horse or pony that has either got laminitis, or is close to getting it. Typically EMS sufferers are also lacking in energy and slow to lose weight.

As owners we do not always realise that our animals have a weight problem. This is partly because weight gain is often gradual, but also because the extra fat is not always around the animal’s middle – a lot of fat is stored in the crest, at the top of the tail, and around the sheaf of geldings. Look closely at your pony; smooth round swellings on the hindquarters or on either side of the tail are all extra fat stores! Ponies with a big crest are at particular risk of laminitis, partly because the fat there is especially active but also because these ponies may not have the typical big ‘grass belly’ and so owners do not recognise the danger.

Q) Is there a test for EMS?

EMS affects horses and ponies of all ages. Although we can often have a good idea that a horse or pony may have EMS from its body shape, the only way to prove it is to take blood tests. In some cases simply testing the blood glucose and insulin levels is enough – if they are higher than normal then EMS is present. Sometimes however the resting levels can be normal even in ponies with EMS, and in these cases we have to give a feed containing glucose powder and test the levels a couple of hours later. Ponies with EMS cannot control their blood glucose normally, so they will have higher levels after such a feed.

Q) What is the treatment for EMS?

EMS is best thought of as a ‘lifestyle disease’, and the only sure way to treat it is by altering the pony’s management. The bad news for sufferers is that this means less food and more exercise! Basically we need to reduce the number of fat cells and so reduce the disruption to the glucose metabolism. To achieve this the following steps are necessary:


- No access to grass, particularly if the horse or pony is currently laminitic

- A diet of hay only, plus a very small amount of a low calorie feed balancer such as Topspec antilam to provide vitamins and minerals

- The hay has to be weighed out, and the pony fed just over one percent of its bodyweight per day. For a 13.2 pony this can be as little as 4kg of hay every 24 hours. The hay is weighed dry, but then soaked in water overnight to reduce sugars. A small electronic scale is best for weighing.

- No tidbits or treats!


- Exercise is an important way to burn calories and lose weight, but it can only be done when any ongoing laminitis has been controlled.


- There is a drug used to help treat EMS, which is called metformin. We may put your horse or pony on this drug for several weeks to help control glucose levels until the diet regime takes effect. It is especially helpful when laminitis means the pony can’t be exercised. In rare cases ponies may be kept on metformin for longer.

- Metformin can help treat EMS, but it will not cure it; to achieve this it is vital that the diet and exercise regime is followed.

Monitoring Weight Loss

- Ponies should be measured around the widest part of the crest and the widest part of the tummy – either with a weigh tape or a tape measure -and a weekly diary kept of the measurements. In this way it is possible to record and track the weight loss.

Other commonly asked questions:

Q) My pony just doesn’t lose weight no matter how little I feed it. What can I do?

If you stick to this regime your pony will lose weight, although it will take a number of weeks. The most important thing is to weigh the hay out carefully. Most of us don’t realise by how much we overfeed our horses.

Q) Will such a strict diet give my horse colic or stomach ulcers?

There is good research to show that horses and ponies do not suffer any ill effects from this management regime. For successful weight loss it is necessary for the pony to be without food for a good number of hours each day. If your pony has constant access to hay, it will not lose any weight

Q) How long does my horse have to stay on the diet?

This is a change of lifestyle rather than a diet – once sufficient weight has been lost the feed can be increased to a maintenance level, but the pony’s weight must be monitored and not allowed to increase. It is better to think of EMS being controlled rather than cured.

Q) Will my pony be able to go out on grass again?

Yes, ponies with EMS that is well controlled can be allowed to graze, although the amount of turnout is always likely to need restricting.