Fatal upper airway obstruction in a pig after general anaesthesia

Pig Sedation and Anesthesia for Medical Research

In clinical veterinary practice, proper training and expertise in anesthesia administration and monitoring are essential. Pigs are suitable experimental animals for many surgical techniques because they are similar in size to humans and have a short reproductive cycle. This makes them ideal for research concerning organ transplantation, cardiovascular surgery, and other procedures that require a large animal model. Sedation and premedication should be administered at the lowest dose to be effective with predictable results and reduced adverse effects, to ensure the safety of both the animal and the team involved in the procedure, with a fast onset and optimizing the induction and maintenance of anesthesia. The goal of induction is to achieve a safe and effective level of anesthesia that ensures patient safety and facilitates research. Most of the time, inhalation anesthesia with endotracheal intubation is the ideal choice for maintenance of anesthesia. The difficulties related to endotracheal intubation of pigs can be overcome by knowing the anatomical peculiarities. Effective analgesia tailored to the specific procedure, the pig's condition, and individual responses to medications should complete the maintenance and recovery protocols, reducing perioperative complications.

Comparison of two sedation protocols, with and without analgesia, in pigs: Assessment of sedation end points and propofol requirements

OBJECTIVE

To compare the effects of intramuscular premedication with a novel nonanalgesic [alfaxalone-midazolam-acepromazine (AMA)] and an analgesic [ketamine-midazolam-detomidine (KMD)] protocol on sedation end points and propofol requirements for induction of anesthesia in swine.

STUDY DESIGN

Prospective experimental study.

ANIMALS

A total of 27 Yorkshire cross gilts weighing approximately 30 kg.

METHODS

Two sedation protocols, AMA and KMD, were compared. Time from intramuscular injection to ataxia, recumbency and nonresponsiveness to tactile stimulation was recorded. The propofol dose requirement for induction of general anesthesia and tracheal intubation, and any adverse events (paddling, twitching), were recorded. Data were tested for normality using a Shapiro-Wilk test. Propofol requirements were compared using a Student's t test. Times from injection to sedation end points were compared using a Mood's test, and significance was confirmed using a Kaplan-Meier curve with Wilcoxon test survival analysis.

RESULTS

Sedation end points were reached significantly faster with KMD than with AMA. Nonresponsiveness occurred in 5 (0-16) and 9.5 (5-36) minutes for KMD and AMA, respectively (p = 0.011). No significant difference (p = 0.437) was found between propofol doses used in either group (KMD; 64.38 ± 5.98 mg, AMA; 72.00 ± 7.57 mg). More adverse events were noted with AMA (11/16 pigs) than with KMD (1/11 pigs).

CONCLUSIONS AND CLINICAL RELEVANCE

In pigs, AMA can be used as a reliable sedation protocol. Frequency of adverse events and time to reach sedation end points between AMA and KMD differed, but the dose of propofol needed to induce general anesthesia was not significantly different.