Clinical and pathologic findings in two draft horses with progressive muscle atrophy, neuromuscular weakness, and abnormal gait characteristic of shivers syndrome.

The research article discusses a study of two Belgian geldings suffering from a severe advanced form of shivers syndrome, characterized by muscle atrophy, weakness, and abnormal gait. Through a series of clinical examinations and necropsies, the study investigates the cause of these symptoms, suggesting that an underlying metabolic myopathy may be responsible.

Examination and Diagnosis

• The study was conducted on two Belgian geldings aged 4 and 14 years.
• These horses exhibited symptoms such as muscle atrophy, weakness, and abnormal gait.
• A neurological examination was conducted on both horses. While there were symptoms of physical weakness and shivers syndrome, there was no evidence of ataxia, a lack of muscle control or coordination of voluntary movements.
• The clinical diagnosis for these horses was neuromuscular weakness and shivers.

Necropsy Findings

• Necropsies, or post-mortem examinations, were conducted on both horses.
• The examination included the pituitary, brain, spinal cord, spinal roots and ganglia, and peripheral nerves.
• No abnormalities, either gross or histologic, were found during these examinations.

Skeletal Muscle Examination

• Multiple skeletal muscle specimens were examined.
• These examinations revealed chronic myopathic changes, indicating ongoing muscle disease, and the presence of periodic acid-Schiff positive, amylase-resistant inclusions within muscle fibers.
• These inclusions are characteristic of equine polysaccharide storage myopathy, a muscle disease in horses causing weakness and stiffness.

Conclusion

• Based on these findings, the article suggests that the underlying cause of muscle weakness and cramping in horses with shivers may be metabolic myopathy, a disorder affecting the metabolism in the muscles.