Effects of halothane and sevoflurane on the electroretinogram of dogs

Abstract

Objective - To study the effects of halothane and sevoflurane on the electroretinogram of dogs. Animals - 6 clinically normal Beagles. Procedure - Beagles were paralyzed by continuous IV administration of muscle relaxant and were artificially ventilated with a gas mixture of nitrous oxide and oxygen during experiments. Corneal electroretinograms were recorded, using full-field stimuli under several recording conditions before and during 1% halothane or 2% sevoflurane inhalation. Results - The amplitude of the scotopic threshold response (STR) and b-wave was significantly decreased by halothane or sevoflurane inhalation, but the degree of decrease in the STR was much greater. In contrast, the amplitudes of oscillatory potentials were increased. The peak latencies of the 3 components tended to be prolonged by inhalation of the anesthetic. There seemed to be no difference between the effects of halothane and sevoflurane. Conclusions - Halothane and sevoflurane strongly depressed the STR in Beagles while moderately depressing the b-wave and increasing oscillatory potential amplitudes. Thus, neither is an appropriate anesthetic for use in recording of the STR in dogs.