Comparative Effect of Epidural Administration of Xylazine or Dexmedetomidine on Echocardiographic Dimensions and Cardiac Indices in Clinically Healthy Donkeys (Equus asinus).

This research study explores and compares the effects of epidural injections of xylazine and dexmedetomidine on echocardiographic dimensions and cardiac functions in healthy donkeys. The study found that both medications induced mild and temporary changes in these physiological measures, requiring careful administration in donkeys with prior cardiovascular issues.

Objective and Methodology

• The research aimed to examine and compare the changes in echocardiographic dimensions and cardiac function indices after epidural injection of two drugs, xylazine and dexmedetomidine, into healthy donkeys.
• The experiment followed a prospective randomized cross-over design, where each donkey served as its own control by receiving all treatments sequentially with adequate washout periods.
• Ten adult donkeys were given three types of treatments – saline solution, xylazine and dexmedetomidine, in the epidural space between the second and third coccygeal vertebrae.
• The researchers made echocardiographic dimensions and heart function measurements using a 2-3.9 MHz sector transducer at predetermined time points after the administration of the pharmaceuticals.

Findings

• Both xylazine and dexmedetomidine induced moderate sedation, complete bilateral perineal analgesia (numbness in the region around the anus) and mild ataxia (lack of muscle control) in all cases.
• There was a marked reduction in the thickness of the interventricular septum at end systole 60 minutes, stroke volume 30-120 minutes, fractional shortening 120 minutes, and ejection fraction 90-120 minutes after administration of xylazine or dexmedetomidine when put in comparison with the saline solution.
• At the same time, there was a significant increase in left ventricular end-diastolic volume 60 minutes post administration of dexmedetomidine versus xylazine and saline. Similarly, the left ventricular internal diameter end-diastole and left ventricular end systolic volume increased noticeably after administration of the drugs when compared with the saline solution.

Conclusion

• This research concludes that the epidural administration of xylazine or dexmedetomidine in donkeys generated a mild and temporary impact on the echocardiographic dimensions and cardiac function indices. This emphasizes that these medications should be judiciously utilized, particularly in donkeys having any pre-existing cardiovascular compromise to prevent exacerbation of underlying conditions.