Preferred Energy Source for Horses with Tying-Up Syndrome and Metabolic Disorders
Veterinarian-recommended feed formulated for horses requiring a low-starch diet
RE•LEVE® is appropriate for any health condition in which a low-starch diet is recommended. Specifically, a low-starch diet may be beneficial for horses prone to the following muscular disorders and metabolic syndromes.
Polysaccharide storage myopathy (PSSM or EPSM)
Recurrent exertional rhabdomyolysis (RER)
These metabolic problems may be triggered or exacerbated by the consumption of soluble carbohydrates found in diets that contain typical concentrates.
Similar Problems, Several Syndromes
Tying-up and exertional rhabdomyolysis (ER) are terms used to describe the sudden and severe muscle cramping that sometimes occurs in performance horses. Studies over the last decade have allowed researchers to identify several types of chronic exertional rhabdomyolysis. Although the syndromes are caused by different cellular and metabolic abnormalities, careful management of the feeding program can often provide relief and allow an affected horse to train and perform at a productive level. Polysaccharide storage myopathy (PSSM) is a type of chronic exertional rhabdomyolysis that is most common in stock-type horses (especially those of Quarter Horse, Paint, and Appaloosa breeding), drafts, and warmbloods. The problem is caused by an abnormal accumulation of glycogen in muscle cells, possibly linked to enhanced insulin sensitivity and rapid clearance of glucose from the blood. After only a few minutes of mild exercise, horses with this condition may exhibit stiffness and reluctance to move. Signs in less severely affected animals include muscle twitching, pawing, and stretching out as if to urinate. While PSSM has been diagnosed in horses less than a year of age, the problem often becomes evident when a young horse is first put into training. Episodes may also be triggered when a fit older horse has a change in management such as being kept in a stall or resuming work after a layoff.
A different glycogen storage disorder, equine polysaccharide storage myopathy (EPSM), is found in drafts, draft crosses, and warmbloods. Horses with EPSM show weakness, muscle wasting, twitching, and difficulty with limb control when backing or holding up a leg. Some important contrasts have been found between EPSM and PSSM, but similar dietary management steps have proven helpful to horses with either condition.
Thoroughbreds, Arabians, Standardbreds, and some warmbloods exhibit yet another muscle problem known as recurrent exertional rhabdomyolysis (RER). The cause of this syndrome is a genetic defect in the regulation of intracellular calcium. The muscle stiffness and cramping of RER are commonly manifested when young horses begin race training and may be seen more frequently as fitness increases. The signs are reportedly more common in horses of nervous temperament and are frequently triggered by some type of stress- or fear-producing incident.
Diagnosis of Specific Syndrome
Although nutritional and exercise history are important clues, an examination of blood and muscle cells must be carried out to determine which type of rhabdomyolysis is the cause of muscle problems in a particular horse. While there is no cure as such for ER, a carefully designed program of nutrition and exercise may provide positive results for many horses. A distinction must be made, and horses diagnosed with PSSM must not be fed typical grain diets.