Effect of sex and gonadectomy on dogs' spatial performance

In order to investigate the effect of sex and gonadectomy on dog's spatial performance, 64 pet dogs were recruited until obtaining four equally sized groups, namely intact males (IM), orchiectomised males (OM), intact females (IF) and ovariectomised females (OF). Dogs were tested in a T-maze paradigm for their performance in learning the way out of the maze, recalling the learned exit after 2 weeks and reversing their learning right after. Sex had an effect on dogs' speed and accuracy in the initial learning task, with IF reaching the learning criterion in fewer trials and making fewer errors than IM; IF also outperformed OF in terms of both speed of learning and accuracy in the learning task. No effect of orchiectomy was found in this stage of the experimental procedure. The better performance of IF was also evident in the percentage of success in both the learning and memory tasks, which were achieved by 100% of the IF, 69% of the IM, 62% of the OF and 56% of the OM. No effect of either sex or gonadectomy was found in the reversal learning task. Results are discussed within current views, which attribute sex-differences in spatial navigation to a sex dimorphism in the deployment of various types of information. In spite of the frequency with which dogs' gonadectomy is advised in most western countries, its consequences on cognitive abilities remain virtually unknown and the present study provides the first evidence that ovariectomy does impact on dogs' functions other than reproductive ones. (C) 2017 Elsevier B.V. All rights reserved.