Postanesthetic rhabdomyolysis in 7 warmblood horses.

The research paper investigates post-anesthetic rhabdomyolysis (muscle tissue breakdown) in seven warmblood horses and describes the associated clinical findings, outcomes, and muscle histopathology.

Details about the Study and Horses

• The study examined seven warmblood horses, consisting of six geldings (neutered males) and a single mare (female), ranging in age from four to eighteen years and weighing between 550 and 703 kg.
• All seven horses developed post-anesthetic myopathy (muscle disorder) despite remaining stable while under general anesthesia. Five of these seven horses were engaged in regular work before they underwent anesthesia.
• The manpower was conducted based on data records taken from Valberg Neuromuscular Diagnostic Laboratory and Michigan State University, spanning from 2016 to 2023.

Clinical Findings and Outcomes

• Following their respective procedures and applications of anesthesia, a prolonged period before the horses were able to stand was observed. Worryingly, three horses were euthanized because they continued to lay recumbent or lay down persistently.
• Symptoms of post-anesthetic rhabdomyolysis recurred five to eleven days after anesthesia in four horses where only one horse survived.
• The symptoms included muscle stiffness, pain, and sweating and the horses struggled to remain standing.
• The study monitored biochemical indicators such as serum creatine kinase activity and lactate concentrations, which were significantly increased as the myopathy developed.

Pathological Findings

• Observations from autopsies showed signs of muscle damage which included complete glycogen depletion in five of the seven horses, acute muscle degeneration in six, and chronic active muscle degeneration in some of the skeletal muscle samples.
• A lab test which is a biopsy of a semimembranosus muscle taken 14 days after anesthesia from the surviving horse showed a small number of glycogen-depleted fibers.

Conclusions

• The study concluded that warmblood horses are susceptible to dangerous post-anesthetic myopathy characterized by acute muscle degeneration, lactic acidosis, and muscle glycogen depletion up to eleven days after anesthesia.
• The researchers proposed close monitoring for two weeks after anesthesia, including the assessment of serum creatine kinase activity and blood lactate levels that could potentially improve outcomes for horses with delayed recovery after anesthesia.