PSSM Diets

Polysaccharide storage myopathy (PSSM) is a muscle disease that affects Quarter horse bloodlines such as American Paint horses and Appaloosas, Draft, Draft crossbreeds and warmbloods. PSSM causes an abnormal accumulation of glycogen and polysaccharide molecules in muscle tissues. Both types of this disease respond positively to regular exercise and diet changes.

  1. Types

    • Scientists and researchers recognize two types of PSSM. An inherited genetic mutation on the GYS1 gene causes Type 1. But not all horses who have from PSSM suffer from this gene mutation. Horses with PSSM, but without all gene mutation, fall into Type 2. As of 2011, scientists are still trying to determine the cause of Type 2 PSSM. Horses suffering from both types of the disease show the same symptoms, but symptoms vary between breeds. Scientists establish a Type 1 diagnosis using a genetics test, while Type 2 is diagnosed through a muscle biopsy.

    Signs

    • The common sign of PSSM is muscle tension or spasms, also known as tying-up. Tying-up episodes consist of muscle stiffness, sweating and reluctance to move. During these episodes, your horse may come across as lazy, tighten its abdomen, demonstrate shifting lameness, and display tremors in its flank area. These symptoms usually occur within the first 10 to 20 minutes of light exercise. After the workout, the horses are in pain due to stiff, hard muscles and may stretch out or roll around. Many horses with PSSM suffer from numerous tying-up episodes each year.

    Exercise

    • Regular exercise helps to prevent future episodes of tying-up in PSSM horses. Exercise burns the glycogen in the muscles so it doesn't build up. Horses with this disease should be taken out of their stalls and put to pasture as often as possible in addition to being exercised. If the animal has been laid-up for an extended period of time, gradually introduce it back to exercise. Keeping PSSM horses in a stall or on an irregular exercise schedule may trigger another tying-up episode.

    Diet

    • Manage PSSM by controlling your horse's diet. Fifteen percent or less of the animal's daily calories should come from starch and sugar, and a minimum of 20 percent of daily calories should come from fat. To accomplish this, feed the horse high-quality grass or legume hay. Eliminate grain hays such as oat hay and barley, if they have remaining seed heads. Administer vitamin E and selenium supplements as well as fat supplements. You can give your horse treats such as apple and carrots in moderation. However, don't give the animal grain or sugar treats.