Recognising and treating Equine Metabolic Syndrome (EMS) is essential to improve insulin sensitivity and reduce the risk of laminitis. Experts also now suspect that horses with EMS may be at greater risk of developing PPID as they get older. EMS is not a disease, it is a cluster of factors that indicate that a horse is at greater risk of developing endocrinopathic laminitis. It is preventable and reversible with correct management.
Often seen in “easy keeper” breeds including native ponies, Arabians, Morgans and Iberians, a horse with EMS will usually have:
1. General obesity or regional adiposity (a cresty neck, filled supraorbital hollows, fat behind the shoulders and around the tailhead, swelling around the sheath/mammory glands);
Often seen in “easy keeper” breeds including native ponies, Arabians, Morgans and Iberians, a horse with EMS will usually have:
1. General obesity or regional adiposity (a cresty neck, filled supraorbital hollows, fat behind the shoulders and around the tailhead, swelling around the sheath/mammory glands);
Above: overweight pony.
Below: correct weight, same pony after weight loss. |
Above: large neck crest.
Below: no crest, same horse after weight loss. |
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Above: filled supraorbital hollows.
Below: same horse, normal supraorbital hollows. 
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Above: swollen sheath on horse with EMS.
Below: same horse, normal sheath. 
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2. Insulin dysregulation - insulin resistance and/or hyperinsulinaemia (indicated by blood tests); and
3. A predisposition to or history of laminitis - signs of chronic laminitis such as hoof rings wider at the heels, a less-than-tight white line and a change of angle in the hoof wall may be seen in the feet, and x-rays may show rotation and remodelling of the pedal bone.
3. A predisposition to or history of laminitis - signs of chronic laminitis such as hoof rings wider at the heels, a less-than-tight white line and a change of angle in the hoof wall may be seen in the feet, and x-rays may show rotation and remodelling of the pedal bone.
Obesity
Obesity develops when horses have too much food and too little exercise. As the horse becomes obese and fat cells become full, the insulin signaling pathway is disrupted, causing insulin resistance. Fat cells release pro-inflammatory chemicals that cause systemic inflammation, and hormones including leptin, a “stop eating” hormone released when the horse has excess energy stored. High levels of leptin cause the target cells to become less receptive, or resistant, to the message to stop eating, so the horse continues to eat and put on weight. Obesity may also affect liver function resulting in reduced insulin clearance and consequent hyperinsulinaemia.
Research has suggested that weight gain has a greater impact on insulin sensitivity in certain breeds, with Arabians becoming insulin resistant when fed excess energy, but Thoroughbreds showing no decrease in insulin sensitivity with weight gain.
Obesity develops when horses have too much food and too little exercise. As the horse becomes obese and fat cells become full, the insulin signaling pathway is disrupted, causing insulin resistance. Fat cells release pro-inflammatory chemicals that cause systemic inflammation, and hormones including leptin, a “stop eating” hormone released when the horse has excess energy stored. High levels of leptin cause the target cells to become less receptive, or resistant, to the message to stop eating, so the horse continues to eat and put on weight. Obesity may also affect liver function resulting in reduced insulin clearance and consequent hyperinsulinaemia.
Research has suggested that weight gain has a greater impact on insulin sensitivity in certain breeds, with Arabians becoming insulin resistant when fed excess energy, but Thoroughbreds showing no decrease in insulin sensitivity with weight gain.
Measurements to help identify obesity should be carried out regularly (e.g. every 2 weeks):
1. Cresty neck score from 0 to 5, with scores of 3 or greater often being seen in horses with EMS. A cresty neck score of 3 is described as “Crest enlarged and thickened, so fat is deposited more heavily in middle of the neck than towards poll and withers, giving a mounded appearance. Crest fills cupped hand and begins losing side-to-side flexibility.”
2. Neck circumference.
1. Cresty neck score from 0 to 5, with scores of 3 or greater often being seen in horses with EMS. A cresty neck score of 3 is described as “Crest enlarged and thickened, so fat is deposited more heavily in middle of the neck than towards poll and withers, giving a mounded appearance. Crest fills cupped hand and begins losing side-to-side flexibility.”
2. Neck circumference.
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3. Bodyweight using scales, a weight tape or calculations from measurements.
4. Body condition scoring – 8 or 9 on the 9 point Henneke scale is considered obese, 6 and 7 overweight. A 0 to 6 scale is also used, with scores of 4 and 5 being considered overweight and obese - see Body Condition Scoring Video.
4. Body condition scoring – 8 or 9 on the 9 point Henneke scale is considered obese, 6 and 7 overweight. A 0 to 6 scale is also used, with scores of 4 and 5 being considered overweight and obese - see Body Condition Scoring Video.
Genetics
Some breeds appear to be more predisposed to EMS
Some breeds appear to be more predisposed to EMS