A Missing Link for the Metabolic Horse

By: Lynda M. Vanden Elzen

We spend a lot of time here talking to customers about how to feed their sugar-sensitive horses.  People call looking for low sugar hay, and inevitably we end up talking about their horses with them.  We like to get a wholistic picture of the horses we are helping to feed so that we can make the best recommendations to their owners.  More often than not, the horse is a mature, sedentary animal, and the owner admits with great guilt that they don’t ride him as often as they should.  More and more, horses are living sedentary lives in stalls and small paddocks, many with the best of everything….except what is one of the most crucial aspects of their welfare – exercise.

The reality is that we can feed a metabolic horse a diet that is low in sugars, but there is a great deal more to it in terms of creating a wholistic plan to help that horse to maintain a healthy weight.  In terms of feeding the sugar-sensitive horse, usually the ideal forage is low in carbohydrates, moderate in protein, and higher in fibre, while still being palatable enough that the horse will eat it.  But I think, just like we tend to do with ourselves, we get very focused on diet, at the expense of considering the importance of exercise.  It is not as simple as “calories in / calories out”; exercise increases muscle mass which burns more calories, decreases leptin resistance, and leads to psychological well-being, which translates to lower cortisol levels and a happier horse.  Horses evolved to move almost constantly and many of their body systems depend on freedom of movement, from their hooves to their skeletal systems, to their lymphatic and cardiovascular systems.

Dr. Juliet Getty, PhD, circulated an article in recent years, “Empty Fields Everywhere – Why Movement is So Important” in which she expressed dismay at driving through Kentucky with its gorgeous, empty fields and ornate barns full of horses kept in stalls.  In that article, she outlined the relationship between exercise and the reduction of insulin resistance:

“Sedentary horses lose muscle mass and can become insulin resistant. Muscle uses a large amount of glucose for energy; the more muscle mass your horse has, the more glucose transporters are produced, leading to increased insulin sensitivity. Therefore, exercise not only burns calories, but reduces insulin resistance. Exercise also helps reduce leptin resistance.”

In another article of Dr. Getty’s, about slowing the progression of PPID (Equine Cushings), she states:

“Don’t neglect exercise. It not only burns calories, but exercise makes cells more receptive to insulin, allowing the horse’s body to burn fat. The blood insulin level declines, thereby reducing inflammation and the risk of laminitis. Exercise also helps protect muscle mass (which the cushingoid horse is losing). Finally, it makes your horse more sensitive (less resistant) to leptin, a hormone that is supposed to tell your horse to stop eating.”

In an article on insulin resistance by Dr. Eleanor Kellon, VMD, she points out:

“The most successful therapy for IR in both humans and horses is exercise and diet control. Exercise primes the muscle to take up glucose by pathways that are independent of insulin, resulting in less work for insulin to do and improved IR. The effect lasts for about 24 hours…There are no magic bullets and no short cuts with IR. Exercise is often the missing element with domestic horses and matching the ancestral exercise level is difficult if not impossible for most people. This necessitates tighter control of sugar and starch in the diet of horses prone to IR.”

Chip, summer 2015

Chip, summer 2015

My own horse, Chip – a morgan/appaloosa cross – is prone to overweight, and I have pictures of his sire, a purebred morgan, who had a huge cresty neck.  Chip is built like a bulldog quarter horse and is metabolically thrifty, and I know he is in a high risk category for developing insulin resistance,   As well, morgan horses are prone genetically to develop insulin resistance and Equine Cushings, so special care must be taken for these horses to keep them in optimal health, especially as they age.  Chip lives out on grass in the dry season here, and normally has to wear a grazing muzzle during daylight hours, to simulate grazing on sparse pasture, and to limit both his overall intake as well as the volume of carbohydrates he is able to consume.   Two summers ago (2014), I wasn’t riding him, and he had to wear his grazing muzzle during daylight hours for the whole season.  Last summer (2015), when I was riding him 7-10 hours a week, or even more some weeks, he was able to live for most of the season without his muzzle while maintaining a healthy body condition score.  He carried less weight than he had the year before, while eating more!  Also worth noting is the fact that 2015 was a drought year, so the grasses were much more stressed (therefore likely higher in sugars) than they had been in 2014, yet he was still able to go muzzle-free! The difference?  Exercise, and lots of it.  I think we grossly underestimate the importance of exercise for these horses, and it doesn’t do them any favours.

We can and should control the diets of our sugar-sensitive horses.  Higher fibre, low sugar, moderate protein hay, mineral balancing, and an adequate amino acid profile are all important for the metabolic horse, but exercise is often overlooked, to the detriment of our equine partners.

 

SOURCES & SUGGESTED READING:

“Empty Fields Everywhere – Why Exercise is So Important” – Dr. Juliet Getty, Ph.D. (http://gettyequinenutrition.biz/library/emptyfieldseverywherewhymovementissoimportant.htm)

“PPID Progression Can Be Slowed Down” – Dr. Juliet Getty, Ph.D. (http://gettyequinenutrition.biz/library/ppidprogressioncanbesloweddown.htm)

“Commentary: Considerations for the IR Horse” – Eleanor Kellon, VMD (http://www.thehorse.com/articles/28821/commentary-considerations-for-the-ir-horse)

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