An analysis of canine hair re-growth after clipping for a surgical procedure


  • This study was funded by the Small Companion Animal Grant, College of Veterinary Medicine, University of Minnesota.

Dr Sheila M. F. Torres, Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University or Minnesota, C339 Veterinary Hospitals, 1352 Boyd Avenue, St. Paul, MN 55108, USA. E-mail:


Abstract  Hair growth and replacement have been studied extensively in humans, sheep and laboratory rodents, but in dogs and other mammalian species few studies have been published. The objectives of this study were: (1) to determine the time required for the hair to re-grow in dogs after clipping for a surgical procedure; (2) to define whether the season of the year influenced the period of time required for re-growth and; (3) to determine if season might influence the telogen: anagen ratio. Eleven Labrador retrievers were recruited during spring, 10 during summer, six during autumn and 10 during winter. Hairs re-grew to their preclipped length in 14.6 weeks, 14.5 weeks, 13.6 weeks and 15.4 weeks when shaved in the spring, summer, autumn and winter, respectively. The differences in these values were not significant suggesting that season has no effect on the rate of hair re-growth in Labrador retrievers housed indoors (P = 0.12). The mean values for the telogen: anagen ratio in each season were: 5.2 (spring), 6.1 (summer), 9.5 (autumn), and 5.3 (winter). The differences in these values also were not significant (P = 0.89). The percentage of hairs in telogen was over 80% in all four seasons.