PSSM in Horses: Muscle Disease Management and Welfare
Polysaccharide storage myopathy (PSSM) causes painful muscle cramping in horses, requiring dietary and exercise management to maintain welfare and function.
Key Facts
- PSSM1 involves a mutation in the GYS1 gene causing abnormal glycogen storage
- PSSM2 encompasses several other myopathy variants with different causes
- Affected horses show muscle stiffness, reluctance to move, pain, and muscle wasting
- Dietary management (low starch, high fat, high fiber) is central to welfare
- Regular appropriate exercise improves clinical signs and welfare in PSSM
Welfare Considerations
PSSM creates welfare challenges through episodic and chronic muscle pain, stiffness, and exercise intolerance. Horses with poorly managed PSSM experience tying-up episodes of severe muscle cramping that cause distress and pain. The dietary and exercise requirements for welfare management can conflict with traditional horse keeping practices. Low-nonstructural carbohydrate diets with supplemental fat, combined with regular light exercise, dramatically improve quality of life for PSSM horses. Education of horse owners and trainers about PSSM is crucial for appropriate welfare management.
What You Can Do
- Switch to a low-starch, high-fat, high-fiber diet as directed by your vet
- Implement daily exercise routines appropriate to the horse's condition
- Never abruptly stop exercise—maintain consistency to prevent tying-up
- Provide a vitamin E supplement to support muscle health
- Work with an equine nutritionist experienced in PSSM management