Postnatal Development of Brainstem Auditory‐Evoked Potentials, Electroretinograms, and Visual‐Evoked Potentials in the Calf

Abstract

Brainstem auditory‐evoked potentials (BAEP), electroretinograms (ERG), and visual‐evoked potentials (VEP) were recorded for eight calves from birth to 56 days and the values compared with previously determined adult responses. The BAEPs, ERGs, and VEPs recorded within the first 24 hours after birth contained all of the peaks seen in adult recordings. Varying degrees of maturation of the responses were documented as changes in latency and amplitude with age. The BAEPs were adult‐like at birth, with latencies falling within the mean, plus or minus one standard deviation, for adult cows. A small but significant decrease in latency with age was seen for the first, second, and fourth peaks of the response. The ERG amplitudes were also within the adult range for the entire period of the study. Latencies to the a‐ and b‐waves declined during the first 14 days and then stabilized at adult values. The VEP latencies decreased with age, with late peaks changing more than early peaks. Latencies of all but the first peak decreased to values less than the adult range. Two VEP amplitudes increased significantly with age. Developmental patterns in the calf and other precocious species are compared to those in altricious (nonprecocious) species. (Journal of Veterinary Internal Medicine 1989; 3:231–237) Copyright © 1989, Wiley Blackwell. All rights reserved