Exertional myopathies including RER and PSSM cause muscle pain and damage in horses. Welfare management through dietary modification and exercise programs significantly improves outcomes.
Exertional myopathy causes acute, severe welfare harm during episodes. The muscle pain and cramping of RER episodes is extreme — affected horses sweat profusely, refuse to move, and show obvious distress. Dark urine from myoglobinuria indicates severe muscle breakdown with renal implications. Emergency management including fluid therapy, pain relief, and muscle relaxation is welfare-critical in acute episodes.
Chronic or recurrent myopathy causes ongoing welfare harm between episodes through subclinical muscle pain, exercise intolerance, and behavioral changes reflecting discomfort. Many horses with undiagnosed myopathies are labeled as unwilling, 'cold-backed,' or difficult rather than their behavior being recognized as pain-driven. Accurate diagnosis transforms welfare outcomes by enabling targeted management.