Metabolism before, during and after anaesthesia in colic and healthy horses.

The research investigated metabolic changes in healthy horses and colic horses before, during, and after anaesthesia. The study found that colic horses, which undergo abdominal surgery, showed heightened levels of certain metabolites before anaesthesia, faced diminished muscle oxygenation during anaesthesia, and experienced increased lipolysis and weight loss after anaesthesia.

Study Overview and Methodology

• The study involved 20 healthy horses and 20 colic horses, which required emergency abdominal surgery. The animals were anaesthetised for an average of 228 and 183 minutes, respectively.
• Blood samples were taken before, during, and up to seven days after anaesthesia for analysing haematology, electrolytes, cortisol, creatine kinase (CK), free fatty acids (FFAs), glycerol, glucose and lactate. Arterial and venous blood gases were also measured up to eight hours post-recovery.
• Gluteal muscle biopsy specimens were obtained at the start and end of anaesthesia, and one hour and one day after recovery to further analyse muscle metabolites.

Key Findings

• Before being anaesthetised, colic horses showed elevated levels of plasma cortisol, FFAs, glycerol, glucose, lactate and CK. They also had lower serum phosphate and potassium levels, and low muscle adenosine triphosphate (ATP) content in several instances.
• Anaesthesia and surgery resulted in decreased plasma FFA and glycerol in colic horses, whereas these levels increased in healthy horses.
• During anaesthesia, an increase in muscle and plasma lactate and plasma phosphate was observed in both healthy and colic horses. The levels of plasma lactate increased further after recovery in colic horses, and plasma FFA and glycerol increased eight hours after recovery.
• Post-anaesthesia, plasma concentrations of CK increased and serum phosphate decreased in both groups.
• On the seventh day after anaesthesia, most parameters were not significantly different between the two groups. However, colic horses had lost an average of 8% of their initial weight.

Conclusions

• Colic horses began the anaesthesia process with altered metabolism and a negative oxygen balance. This observation suggests that their disease condition and possible pre-surgery circumstances such as hours of starvation and long trailer rides could have affected their muscle energy reserves.
• All the horses, both healthy and colic, showed insufficient muscle oxygenation during anaesthesia, with colic horses exhibiting this to a greater extent.
• After anaesthesia, colic horses showed an increased rate of lipolysis and weight loss, suggesting they experienced a negative energy balance during their first post-operative week.