Does My Horse or Pony Have Metabolic Syndrome?

We’ve all seen them, the horse in the field looking like Hannibal Lecter in a muzzle. It’s not keeping them from biting; it’s keeping him from eating! Grazing Muzzles have become an unfortunate necessity for many horses today. Much like people, horses are suffering from the effects of overeating and obesity. These horses seem to get fat on air and are often called “easy keepers.” There is likely a genetic predisposition that makes these horses very efficient at utilizing calories and, in turn, makes them require a lower plane of nutrition than their naturally thinner pasture mates. The term Equine Metabolic Syndrome has been used to describe this condition. The four features of the syndrome are:

  • Obesity
  • Regional adiposity (fat deposits)
  • Insulin resistance
  • Laminitis

The results of the syndrome in horses can be devastating, if not managed properly.

Although Equine Metabolic Syndrome can affect any breed, pony breeds seem to be overrepresented. Horses 5-15 years of age are most commonly affected, but again, almost all age groups have been affected. Environmental conditions certainly are part of the picture, with problems occurring when the pasture is in growth or stress phases, but genetic predisposition comes into play, as not all horses out on the same pasture will be affected.

Diagnosis of Equine Metabolic Syndrome is based on the clinical presentation of the horse and blood tests. Regional adiposity is easy to recognize as the cresty neck and fat pads on the barrel and croup. Resting insulin concentrations can be measured after the horse has been fasted for 12 hours. This is an easy and useful test, but can be affected by pain from laminitis or if the horse eats too close to the time the blood is drawn. Have your TEVA veterinarian examine your horse immediately if you notice lameness. Sensitivity to foot testers at the toes of the feet and rotation of the coffin bone on radiographs are diagnostic for laminitis. Finally, it is important in the older horse to test the ACTH levels to make sure that they don’t have Cushing’s disease.

How Do I Treat Equine Metabolic Syndrome?

Dietary Management is the most important aspect in managing horses with Equine Metabolic Syndrome. Obese horses should be placed on diets to promote weight loss. Most of these horses can have limited hay or pasture (hence the grazing muzzle!) and access to salt and minerals. These horses DO NOT need grain. They should be fed hay at 1.5-2% of their body weight (about 15-20 lbs for a 1000 lbs horse). You should weigh your hay to make sure you are not overfeeding. Decrease the amount of hay if your horse has access to pasture. Ask your TEVA veterinarian if your individual horse needs any vitamin or protein supplementation based on your situation.

What about Exercise?

Exercise is the second ingredient to managing Equine Metabolic Syndrome. Obviously, laminitic horses should not be exercised until their pain is gone, the rotation of the coffin bone is corrected, and the inflammation of the foot is stabilized. Non-laminitic horses should receive daily exercise to promote weight loss. Just like with people, the only way to lose weight is to burn more calories than you consume. We can restrict calories only so far: so that means we must exercise our horses. This can include walking on a lead, lunging or riding. Any type of exercise is better than none! Just do it!

How about Medications?

Some medications can be used to help with weight loss such as levothyroxine sodium or metformin. These are used in individual cases and can be discussed with your TEVA veterinarian.
So….as you watch the grass grow, watch your horse’s weight too. Consider a grazing muzzle if he is gaining weight and is on pasture. Consult with your TEVA veterinarian if you have questions as to whether or not your horse might have Equine Metabolic Syndrome or insulin resistance.

Registered 2011 by Equestrian Collections
Author: Sallie S. Hyman, VMD, DACVIM, CVA

Information in this article is for educational purposes only and is not a substitute for evaluation by an equine professional. In particular, all horse owners should seek advice and treatment from a licensed veterinarian, such as TEVA, for their horses' medical care.

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