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Tying Up (Exertional Myopathy) in Horses
Buckeye Nutrition Technical Bulletin
Exertional Myopathy (aka: Tying Up) is a common cause of poor performance in horses. These muscle disorders can range in severity from mild muscle cramping and strain to damaged muscles (Exertional Rhabdomyolysis). These episodes can be caused by excess carbohydrate, low Vitamin E or low Selenium, and can be drastically reduced, or even eliminated, by implementing a proper exercise and nutrition program.
Some of these conditions, however, are caused by factors other than exercise, such as HYPP and EPSM. In order to eliminate or reduce the episodes, a determination must be made for why the muscle is not functioning properly.
Has the horse been diagnosed with HYPP (Hyperkalemic Periodic Paralysis)? This is an inherited genetic defect where horses are sensitive to high levels of potassium. If the horse is HYPP positive, please see our Technical Bulletin EB-06 regarding this topic.
Has the horse been diagnosed with EPSM (Equine Polysaccharide Storage Myopathy)? This is a muscle condition involving the improper utilization of glycogen in the muscle. If the horse is EPSM positive, see our Technical Bulletin EB-05 for proper feeding of the EPSM positive horse.
A horse that is tying up may have a variety of symptoms ranging from reluctance to move, exhaustion, rapid heart rate, dehydration and collapse. It is important to receive a correct diagnosis of tying up, as it is oftentimes confused with colic. Your veterinarian can make this diagnosis based on the horse’s history of muscle cramping and stiffness, and may take a blood sample to look for elevated muscle enzymes in the blood.
Once it has been determined that EPSM or HYPP are not a factor in the episode, it is important to consider the correlation between nutrition and exercise regimens. A diet high in carbohydrates fed on days of rest can induce tying up. Vitamin E and selenium deficiency can cause acute episodes. The Buckeye Harvest Salt contains selenium and the Grass Plus and Alfa Plus Mineral/Vitamins contain Vitamin E to complement the levels in the other Buckeye horse feeds. Electrolyte imbalances are also a contributor to tying up. Replace the electrolytes with the Buckeye Perform’N Win according to package feeding directions.
Recommended Nutrition and Exercise Regimen
Is the horse tying up in the beginning of its work or late in the work? If the horse is tying up late in the work, usually the episode is caused by fatigue. If the horse is tying up early in its work, there may be several factors causing the occurrence. Some of the causes of tying up for a fit horse early in work are:
a.) Erratic activity. It is important to exercise consistently.
b.) On days of rest, feed accordingly. Don’t feed as much grain as you would on days where the horse will be hard at work. Gro’N Win® or Alfa Gro’N Win® (depending on forage type fed) are ideal rations for the horse who has inconsistent work loads from day to day. Oats (or corn) are used for calories and can be increased or decreased according to the workload, where the level of Gro’N Win® or Alfa Gro’N Win® is maintained to ensure adequate levels of minerals and vitamins are fed. With a traditional grain mix, if the amount of feed is decreased on light work and rest days, the minerals and vitamins that the horse receives are decreased.
c.) Feed free choice good quality hay every day to maintain normal gut function.
d.) Feed less than 50% of the total daily ration in grain, over 50% in hay.
e.) Use a calorie source that is derived from fat as opposed to carbohydrates (ie; corn, oats) by supplementing with Buckeye’s Ultimate Finish.
Reprinted with permission from Buckeye Nutrition. Visit them at www.buckeyenutrition.com