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

Comparative evaluation of the sedative and analgesic effects of caudal epidural administration of lidocaine alone or in combination with xylazine, detomidine, medetomidine and dexmedetomidine in Mediterranean miniature donkeys

The present study aimed to compare the sedative and analgesic effects of caudal epidural administration of lidocaine alone or in combination with four different α₂-adrenergic agonists in Mediterranean miniature donkeys. A total of ten clinically healthy (5 males and 5 females) Mediterranean miniature donkeys with an age of 5 ± 1 years, a weight of 100 ± 2 kg and a height at the withers of 0.8 ± 0.06 m (mean ± standard deviation) were used in experimental, crossover (Latin square), randomized and blinded study. Animals were assigned to five treatment groups including lidocaine alone (0.22 mg kg^-1), or associated with one among xylazine (0.17 mg kg^-1), detomidine (30 μg kg^-1), medetomidine (15 μg kg^-1), dexmedetomidine (5 μg kg^-1) with a minimum washout period of 8 days between treatments. The degree of sedation was investigated using a simple descriptive scale of 0-3. Sedation scores were compared at each time using nonparametric (Kruskal-Wallis and Mann-Whitney U) tests. Analgesia was assessed by pinprick test. Sedation was greater in lidocaine/α₂-adrenergic agonist groups than in lidocaine group at 45-75 minutes after drug administration (p < 0.05). There were no significant differences among groups in time to onset of analgesia and ataxia and also in number of animals with complete perineal analgesia and ataxia. Duration of analgesia and ataxia were longer in lidocaine/α₂-adrenergic agonist groups than in lidocaine (p < 0.05). There were no significant differences among lidocaine/α₂-adrenergic agonist groups in sedation score and duration of analgesia and ataxia. No significant differences were observed in heart and respiratory rate and also rectal temperature at any time points between groups and within groups. Caudal epidural administration of α₂- adrenergic agonists associated with lidocaine resulted in sedative effects on Mediterranean miniature donkeys, while lidocaine alone did not induce sedation. These drugs associations should be considered when superior analgesia is advocated.

Assessment of the Cardiac Functions Using Full Conventional Echocardiography with Tissue Doppler Imaging before and after Xylazine Sedation in Male Shiba Goats

The present study aimed to provide a complete conventional echocardiographic protocol in adult male Shiba goats by using two-dimensional, M-mode, Pulsed Wave Doppler, and tissue Doppler imaging (TDI) echocardiography, and to study concomitantly xylazine-induced alteration of cardiac functions in a highly sensitive species. For this purpose, 12 male Shiba goats were included and complete conventional echocardiography from the standard right and left parasternal views was carried to report the echocardiographic data in male Shiba goats, and also before and after xylazine (Pre-Xyl and Post-Xyl) administration (0.05 mg/IM/kg). Results revealed that the full echocardiographic protocol was feasible in all goats through different cardiac windows and good Doppler alignment was achieved with non-significant variability for assessment of the left ventricular dimensions, trans-pulmonary, trans-aortic, and trans-mitral blood flow. The TDI, which was not reported previously in goats, was successfully assessed from the standard left apical view and showed distinct systolic and diastolic patterns. Xylazine administration was found to significantly reduce heart rate, fractional shortening, and cardiac output as well as the Doppler hemodynamic parameters of the pulmonary artery, aortic and mitral inflows (p < 0.05). For TDI, the Post-Xyl group revealed a significant decrease in the myocardial velocities of the septal and lateral wall of the left ventricle. The present study provides, for the first time, complete data of conventional echocardiography in male goats using the full protocol, which is routinely used in pet's practice. Further, we illustrate in-depth the adverse effect of short-term sedative, xylazine, as used under field conditions and emphasize a simultaneous reduction in both systolic and diastolic cardiac function in goats based on full echocardiography assessment of the heart.