Caudal epidural injection of a combination of ketamine and xylazine for perineal analgesia in horses.

This study investigated the effects of injecting a mix of ketamine and xylazine into horses to manage pain in the tail, perineal region, anus, and vulva. The researchers found that it resulted in significant pain relief, with sedative and cardiorespiratory effects that were minimal.

Methodology

• It involved ten healthy horses with an average weight of 329.5kg ± 25.4kg.
• Ketamine (at a dosage of 1mg per kg of the horse’s weight) and xylazine (at a dosage of 0.5mg per kg of the horse’s weight) were mixed in a syringe and injected into the first intercoccygeal (C1^C2) epidural space. This is the space between the first and second vertebrae of the horse’s tail.
• The observer measured the onset, duration, and extent of analgesia (pain relief) at 10-second intervals using a pin-prick test. The horse’s response to the pin prick was given a score between 1 and 3, with 1 meaning no response, 2 indicating a reduced response, and 3 signifying a normal response.
• Cardiorespiratory data, including heart rate, respiratory rate, and rectal temperature, were recorded at various intervals post-injection and compared to pre-injection (control) values. Statistical significance was determined with a p-value of less than 0.05.

Results

• The mix of ketamine and xylazine provided analgesia to the tail, perineal region, anus, and vulva within 5 to 9 minutes of administration. This relief lasted for over 120 minutes. Some horses also noted analgesia in the thigh and flank areas.
• Mild sedation, characterized by drooping of the head and lower lip, was observed after 20 minutes, but the horses remained upright.
• There was a significant decrease in heart rate from 35.5 to 31.83 beats per minute at 15 minutes post-injection. Similarly, the respiratory rate decreased significantly at 30 minutes following injection. However, rectal temperature did not show any significant change.

Conclusion

• The study concluded that administering a combination of ketamine and xylazine epidurally resulted in effective pain relief to the caudal region in horses.
• This treatment approach led to minimal impacts on heart and respiratory rates, making it a possible safe and effective form of analgesia for horses.