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The effects of medetomidine hydrochloride on the electroretinogram of normal dogs |
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| Authors: | Joanna C Norman Kristina Narfström† Paul M Barrett |
| Institution: | Eye Care for Animals, 2316 W. Northern Avenue, Phoenix, AZ 85201;;Department of Medicine and Surgery, College of Veterinary Medicine, A379 Clydesdale Hall, University of Missouri-Columbia, Columbia, MO 65211 |
| Abstract: | Purpose To determine the effects of a standardized intravenous dose of an α-2 agonist (Domitor Methods Twenty-five normal dogs were used to collect ERG responses including a- and b-wave implicit times (IT) and amplitudes (AMP) before and after administration of medetomidine. Dogs were dark adapted for 20 min and ERGs were obtained using the HMsERG (RetVetCorp Inc., Columbia, MO). The QuickRetCheck protocol (Narfström) was employed to provide the following flash intensities: 10 mcd s/m Results The P value for the effect of medetomidine on each of the ERG responses was < 0.01. The estimates of the effect of medetomidine were (+)1.35 ms, (–)23 µV, (+)3.16 ms, and (–)47 µV for the a-wave IT, a-wave AMP, b-wave IT, and the b-wave AMP, respectively. Conclusions Medetomidine significantly prolongs the implicit time and lowers the amplitude response of both the a- and b-waves in normal dogs at all flash intensities examined. Clinically, however, medetomidine only minimally affects the retinal responses and is a viable choice for use in dog ERGs. |
| Keywords: | amplitude electroretinogram implicit time medetomidine hydrochloride normal dog sedation |