Equine Metabolic Syndrome (EMS)

The term, EMS (Equine Metabolic Syndrome) describes a group of risk factors linked to the horse’s hormone system and the most serious potential consequence is laminitis.

Insulin Dysregulation (ID) ID is a broader term that includes insulin resistance (IR) leading to high insulin levels at rest (hyperinsulinemia) and is thought to be the main characteristic of EMS that predisposes the horse to laminitis.

Insulin resistance means the horse’s body does not respond to insulin as well as it should. During digestion, some elements of the feed are broken down into glucose (sugar) molecules and absorbed into the blood stream causing blood sugar levels to rise naturally after a meal. The pancreas then releases the hormone, insulin, which helps move glucose from the blood into muscle and fat cells.

Cells use glucose for energy, exercise and growth, or store it as glycogen or fat for later use. With insulin resistance, the liver, muscles or fat cells respond less well to insulin making it harder to clear glucose from the blood. The pancreas then releases more insulin to compensate, which can lead to higher resting insulin levels in the blood, called hyperinsulinemia, which research shows can cause laminitis.

Signs & Symptoms of EMS

Horse and ponies with EMS may display one or more of the following:

Obesity – abnormal fat distribution - typically an enlarged crest and fat pads
Recurrent laminitis
Difficulty losing weight

If your horse shows one or more of these signs, contact your vet. Your horse’s history may suggest EMS, but tests are needed to confirm the diagnosis. These measure insulin levels at rest and/or how blood sugar and insulin levels change after glucose (sugar) is given by mouth or injection into a vein. Horses with EMS may have more insulin than expected for their blood sugar level at rest and their insulin levels may also rise more than expected, after they are given glucose.

Management

Strict management is required for weight loss and to improve insulin sensitivity. If diet AND exercise are not controlled simultaneously, the efficacy of weight loss is considerably lower.

Diet should focus on reducing the non-structural carbohydrate (NSC: starch and sugar) intake so blood sugar and insulin levels can be managed more easily.
Energy or calories supplied by the diet may need to be restricted, whilst adequate vitamins, minerals and quality protein are being provided.
Daily low intensity exercise encourages weight loss and helps to improve insulin sensitivity, providing laminitis is not a limiting factor.
Any changes in management, including diet, need to be made slowly over 2-3 weeks. Safe, significant weight loss can take upwards of 9-12 months.
Weight and condition should be monitored every 1 to 2 weeks to recognise progression over time. The use of weightapes (around the girth and crest), and body condition and “cresty neck” scoring are ideal.
Where possible, using the winter to your advantage for weight loss is ideal eg. by use of lighter weight rugs to encourage fat usage for temperature maintenance.
It is important that management and diet maintain trickle feeding and a continuous flow of fibre through the digestive system, as there is evidence that this reduces peaks and troughs in the levels of insulin and leptin in the blood stream. Leptin is produced by fatty tissue and is thought to regulate fat storage so avoiding peak levels could reduce the risk of excess fat deposition.
Small meals will also help to minimise blood sugar and insulin peaks.

Medication

For horses that do not respond to strict dietary and exercise management, vets may recommend medication, to promote weight loss and improve insulin sensitivity. However, this should not be seen as a replacement to reducing calorie intake and increasing exercise.

Encouraging Weight Loss/Waistline Control through Diet

Forage

Choose hay or haylage with a water-soluble carbohydrate (WSC)* content below 10-12% to help control sugar intake. WSC includes sugars and fructan which only laboratory testing can confirm.
Soaking hay for up to 12 hours can reduce its WSC content. Increase the soaking time gradually, as soaked hay may be less appealing to your horse. Take extra care in warm weather, to avoid fermentation or bacterial growth.
Good quality straw is low in calories and high in fibre and can replace up to 30 – 50% of the forage ration, though is not suitable for horses with dental problems.
Forage intake should be restricted to the equivalent of 1.5% of the horse’s bodyweight per day, on a dry matter basis. Allow 1.8% of bodyweight, of fresh hay daily to account for its moisture content (around 15%) and to meet minimum fibre requirements. If soaking, weigh out 2.1% of bodyweight, as dry matter can be lost during soaking.
Use small-holed nets or other methods to make forage rations last longer and to keep the horse chewing.
Manage time at grass carefully to limit sugar and fructan intake. Turning out very late at night, when grass fructan and sugar levels are lowest, and ensuring the horse is brought in by mid-morning, is safest. Avoid turning out onto pastures during cold, bright conditions, (e.g. frosty mornings), when the fructan and sugar levels increase.
As well as choosing turnout times carefully, you may need to limit how much grass your horse/pony can eat. Options include strip grazing, a grazing muzzle, or turnout in a grass-free area (a dry lot). If there is no grass, provide suitable forage, such as soaked hay.
Natural Meadow Cobs, Light Chaff or Speedi-Beet may be fed as low calorie alternative or additional fibre sources, as long as overall fibre/calorie intake is controlled.

Concentrates

The best way to provide a balanced diet is to feed a low NSC (starch and sugar)* feed, like Lo-Cal or Performance Balancer, to supply those nutrients likely to be lacking in forage, without unwanted calories.
Light Chaff or Natural Meadow Cobs can be fed with the balancer, to encourage chewing, as can small amounts of Speedi-Beet. (1 Baileys mug of dry Speedi-Beet soaked with 5 mugs of water makes half a bucket of beet with fewer calories than a Stubbs scoop of Light Chaff).
In the less common case where you might need to provide a higher calorie feed, consider feeding larger amounts of Speedi Beet and/or a higher calorie chaff, such as Alfalfa Plus Oil. Straight oil, along with appropriate antioxidant (vitamin E) support, can be fed in addition to further increase calorie intake.

* Understanding starch and sugar

What the terms used for starch and sugar mean:

Non-structural carbohydrates (NSC) include starch and water-soluble carbohydrates (WSC).

Water-soluble carbohydrates (WSC) are mainly simple sugars and fructan. Fructan is a form of stored sugar found in most UK grasses.

WSC matters most for grass-based forage, which contains little starch. NSC may be more relevant for concentrate feeds which could contain starch from cereals or cereal by-products.

As each horse is an individual, if you have any queries about feeding your EMS equine, do contact a Baileys Nutritionist on 01371 850247, nutrition@baileyshorsefeeds.co.uk or visit www.baileyshorsefeeds.co.uk.