If you have a horse that has been diagnosed with a genetic muscle disorder such as Polysaccharide Storage Myopathy (PSSM) or Recurrent Rhabdomyolysis (RER), you’ve likely heard about the benefits of switching to a high fat/low NSC horse feed. But how is a high fat diet beneficial for a horse exactly?
To begin with, it’s important to note that while PSSM and RER are two different conditions, both cause irregularities in the cells which can lead to tying up. Therefore, both are treated similarly when it comes to nutrition.
Research has shown that reducing or eliminating dietary carbohydrates and replacing them with fat limits the amount of sugar that can be converted into glycogen in the muscles; this is critical for PSSM horses but is also beneficial for RER horses.
Fat as energy
Fats and oils belong to a class of molecules called lipids which come as either a single molecule or a chain of molecules, known as a fatty acid. Fatty acids vary in length but can be further subdivided into 2 categories: saturated and unsaturated.
Saturated fats mainly come from animal sources, while unsaturated fats usually come from plant sources.
The most common fat sources in a horse’s diet are vegetable oils, rice bran, and flaxseed.
For horses, the majority of fat digestion occurs in the small intestine, but some fat moves on to the liver, adipose tissue, or to other parts of the body where it can be either stored or utilized as energy.
In fact, fat contains over twice the amount of energy as either carbohydrates or protein, and studies have shown that when fat is substituted for carbohydrates in the diet, blood glucose and insulin responses are also reduced.
Low carb (low NSC) horse feed
Non-structural carbohydrates (NSCs) are found in corn, wheat, oats, barley and molasses, which are all common feed ingredients, but as stated previously, avoiding diets high in carbohydrates is crucial for both RER and PSSM horses.
That is why many feed companies now offer high-fat diets specifically designed for these sensitive horses.
However, keep in mind that forage--both grasses and some types of hay-- is another common source of NSCs. Therefore, it’s important to limit green pasture for PSSM horses, especially, and get your hay tested as well. Having an NSC level of 12% or lower in your forage (think: low carb horse hay) is best for these animals. Studies have shown that RER horses can tolerate higher NSC levels in forage, but caution is still advised.
The importance of equine exercise training
Though feeding high fat feeds can make a big difference in equine muscle disorders, we can’t forget the importance of exercise, which suppresses sugar uptake and also helps horses to better metabolize sugars.
Additionally, PSSM horses use excess glycogen as fuel, so this leads to less accumulation in the muscles. As a result, daily exercise (without days off) is recommended for any horse diagnosed with a muscle disease. In fact, studies show that while 50% of PSSM horses improve with diet changes alone, 90% improve with both diet changes AND exercise.
When managing a horse with muscle disorders, diet and exercise are paramount to their continued success. As a piece of the diet puzzle, specific supplements, made with high-potency antioxidants, can assist in your horse’s quality of life. Follow these recommendations, along with cultivating a close relationship with your veterinarian, and you will find yourself a very happy and healthy horse!