An epidemiological study of myopathies in Warmblood horses.
Authors: Hunt L M, Valberg S J, Steffenhagen K, McCue M E
Journal: Equine veterinary journal
Summary
# Editorial Summary: Myopathies in Warmblood Horses Muscular disorders in Warmbloods have received limited attention in the literature despite their clinical significance, prompting Hunt and colleagues to characterise the prevalence, presentation and management response of myopathies in this population using muscle biopsy submissions to a specialist diagnostic laboratory. Polysaccharide storage myopathy (PSSM) emerged as the predominant condition, affecting 55% of the 132 biopsied horses, followed by recurrent exertional rhabdomyolysis, neurogenic/myogenic atrophy and non-specific myopathic changes, with gait abnormalities and exertional myositis being frequent presenting signs across diagnostic categories. Crucially, owners who implemented low-starch, fat-supplemented diets alongside consistent daily exercise reported clinical improvement in 71% of PSSM cases and 68% of all affected horses with completed follow-up questionnaires, regardless of the underlying myopathy diagnosis. These findings underscore the value of muscle biopsy in differentiating myopathic conditions in Warmbloods and highlight that dietary modification and exercise prescription represent fundamental management strategies applicable across multiple myopathies rather than PSSM alone. For practitioners managing performance or behavioural issues in Warmbloods, consideration of underlying muscular pathology combined with evidence-based nutritional and conditioning interventions offers a tangible pathway to improving clinical outcomes.
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Practical Takeaways
- •Muscle biopsy is a valuable diagnostic tool for identifying specific myopathies in Warmblood horses presenting with gait abnormalities or exertional rhabdomyolysis
- •Dietary management (low starch, fat-supplemented) combined with consistent daily exercise should be the first-line management approach, with over two-thirds of horses showing clinical improvement
- •PSSM is highly prevalent in Warmblood breeds; consider this diagnosis early in horses with typical presentations, regardless of age, sex or management history
Key Findings
- •PSSM was the most common myopathy in Warmblood horses (72/132, 55%), followed by RER (7/132, 5%) and neurogenic/myogenic atrophy (7/132, 5%)
- •Gait abnormality, tying-up, Shivers, muscle fasciculations and atrophy were common presenting clinical signs across myopathy types
- •Low starch fat-supplemented diet combined with regular daily exercise improved clinical signs in 68% of affected horses (19/28) and 71% of PSSM-diagnosed horses (15/21)
- •No differences in sex, age, breed, history or management were identified between control, PSSM and non-PSSM horses