Effects of Alphaxalone, Medetomidine, and Xylazine on Electroretinography of Domestic Pigeons (Columba livia)

Abstract

This study was conducted to compare the effects of 3 different sedative agents on electroretinography (ERG) in domestic pigeons (Columba livia). Alphaxalone, medetomidine, and xylazine were used with one week washout period. Six pigeons were sedated and underwent the modified electroretinography protocol adapted from the standardized protocol for dogs. The scotopic mixed rod and cone response was recorded after 20 minutes of dark adaptation, and the photopic cone response and photopic flicker response were recorded after 10 minutes of light adaptation. One-way ANOVA was used to compare the a- and b-wave implicit time and amplitude. No significant differences in the scotopic mixed rod and cone response were observed among all 3 sedatives used. Compared to alphaxalone, medetomidine significantly prolonged the a-wave implicit time and depressed the b-wave amplitude of photopic cone response (P < 0.05). Compared to alphaxalone, medetomidine also significantly prolonged the peak implicit time of photopic flicker response (P < 0.05). There were no significant differences on all photopic responses of xylazine when compared to both alphaxalone and medetomidine. In conclusion, medetomidine has a depressant effect on photopic electroretinography in pigeons at a dosage that produced light sedation. Alphaxalone could be a better option than medetomidine and, to a lesser extent, xylazine for ERG recording in pigeons.

Keywords: alphaxalone, electroretinography, medetomidine, pigeon, sedation, xylazine.