A retrospective survey of anaesthesia in horses with colic.

This research work focused on identifying complications that could arise during and after anaesthesia in horses dealing with colic, and how these complications relate to the types of drugs used for the induction or maintenance of the anaesthesia.

Objective and Methodology

• The objective of this study was to identify the type of complications that are likely to occur during and after anaesthesia in horses suffering from colic, and to establish if there’s a relationship between these complications and the type of drugs used during the induction or maintenance of anaesthesia.
• The study involved 239 anaesthetised horses on 250 different occasions between January 1985 and May 1987.

Findings

• 189 out of these horses were successfully recovered from 200 anaesthetic episodes.
• Most horses were administered xylazine and guaifenesin with either thiobarbiturate (68 per cent) or ketamine (24 per cent) while anaesthesia was maintained with either halothane (51 per cent), isoflurane (43 per cent), or first halothane then isoflurane (6 per cent). The majority (69 per cent), were also given an opioid.
• The study found that hypotension or tachycardia were recorded in 15 and 13 per cent of anaesthesias, respectively. Arterial PO2 was less than 13.3 kPa in 17 per cent of 175 anaesthesias. However, these complications were not associated with any specific anaesthetic agent.
• About 11.5 per cent of anaesthesias had hypertension, and this was more frequent during isoflurane anaesthesia.
• The mean duration of anaesthesia was 126 minutes and did not alter whether the horses were given thiobarbiturate or ketamine, halothane or isoflurane. The recovery time from anaesthesia was about 63 minutes on average and didn’t vary depending on the anaesthetic agent used.
• Horses that showed signs of excitement or had difficulty standing up during recovery had a significantly longer duration of anaesthesia, but this wasn’t tied to any specific anaesthetic agent.
• Out of the 189 horses, 148 (75 per cent) survived and were discharged from the hospital. Horses that didn’t survived experienced more anaesthetic complications, and had longer durations of anaesthesia.