Effects of xylazine and adrenaline combinations: Preliminary clinical application for non-surgical protocols of nephrosplenic entrapment in horses

Abstract

Background and Aim: The medical treatment of horses with nephrosplenic entrapment (NSE) of the large colon through administrating phenylephrine and rolling during general anesthesia was effective and less expensive than surgical treatment. However, the selection of drugs for non-surgical treatment of NSE is not a usual method for clinical practice. This study aimed to identify the effects of combined drugs on the cardiac and splenic response in horses and provide information on the NSE of the large colon for clinical application. Materials and Methods: Six healthy Thai native crossbred horses were enrolled in this study. Horses received two protocols with a withdrawal period of 14 days: Group 1 received xylazine (0.5 mg/kg IV) and adrenaline (1 mcg/kg IV), and Group 2 received xylazine (0.5 mg/kg IV) and adrenaline (3 mcg/kg IV). Heart rate (HR), HR variability (HRV), heart dimensions, and the splenic response of six horses were measured before the sedation, 30 and 60 min later, and 65, 70, 75, 80, 90, and 100 min after adrenaline administration. Doppler was used to obtain systolic blood pressure. Results: The HRV low-frequency and high-frequency power ratios decreased after using xylazine. Hypertension was observed after adrenaline administration. In this study, there were only minimal differences in the HR and respiratory rate between groups. However, overall cardiac and splenic parameters were statistically higher in Group 2. Conclusion: This study suggested that xylazine and three micrograms of adrenaline preserved the cardiac autonomic activity balance and were safe to use non-surgical applicability in horses.

Suspected postoperative phenylephrine‐associated pulmonary haemorrhage in a horse with nephrosplenic entrapment of the large colon

“…4 Adrenaline, combined with xylazine, has recently been reported as an alternative to phenylephrine administration in six horses. 5 If medical treatment fails, the colon can be surgically repositioned via a standing flank laparotomy 6 or a ventral midline coeliotomy. 7 If colon reposition is still impaired due to the size of the spleen, a single injection of phenylephrine intra-spleen intraoperatively has been recently reported as a successful alternative.…”

“…Phenylephrine, followed by moderate exercise, is used to decrease the size of the spleen and allow the large colon to return to its normal position 4 . Adrenaline, combined with xylazine, has recently been reported as an alternative to phenylephrine administration in six horses 5 . If medical treatment fails, the colon can be surgically repositioned via a standing flank laparotomy 6 or a ventral midline coeliotomy 7 .…”