Polysaccharide storage myopathy
Also known as: PSSM
Hereditary
Polysaccharide storage myopathy (PSSM) is an inherited muscle disorder in which abnormal sugar (glycogen) accumulates in muscle cells. Type 1 is caused by a known GYS1 mutation common in Quarter Horses and draft breeds. Affected horses suffer recurrent tying-up, stiffness, and reluctance to work.
Quick facts
- Type:
- Genetic
- Typical onset:
- Chronic
- Body systems:
- Muscular, Metabolic
- Affected species:
- HORSE
Sources & references
- Merck Veterinary Manual — Describes glycogen-storage myopathy, the GYS1 mutation, and dietary management.
- OMIA — OMIA entry for type 1 polysaccharide storage myopathy in the horse.
This content is for educational purposes and is not a substitute for professional veterinary advice. If you are worried about your pet, contact your veterinarian.