Abstract
Serotonin is a neurotransmitter synthesized by the amino acid tryptophan, that has the potential to impact the behaviour and activity of dogs. The objective of this study was to assess the effects of supplemental tryptophan and a 12-week incremental training regimen on the voluntary activity and behaviour of client-owned Siberian Huskies. Sixteen dogs were blocked for age, BW and sex and then randomly allocated to either the control or treatment group. Both groups were fed the same dry extruded diet; however, the treatment group were supplemented with tryptophan to achieve a tryptophan: large neutral amino acid ratio of 0.075:1. Once a week, a 5-minute video recording was taken immediately pre- and post- exercise to evaluate dogs’ behaviours. Activity monitors were used to record voluntary activity on both training and rest days. Linear regression analysis was used to assess the relationship between training week and time spent performing each behaviour. Additionally, a repeated measure mixed model was used to test differences between diet groups and training week for both behavioural and activity count data. The time spent performing agonistic behaviours prior to exercise was negatively associated with week for treatment dogs (β = -0.32, 95% CI [-0.55, -0.10], P < 0.05) and no change was observed for control dogs (β = -0.13, 95% CI [-0.41, 0.15], P > 0.10). Treatment did not have any effect on activity levels (P > 0.10). For all dogs, locomotive behaviours decreased prior to exercise as weeks progressed (P < 0.05), while run day voluntary activity depended on the distance run that day (P < 0.05). These data suggest that sled dogs experience an exercise-induced reduction in voluntary locomotion in response to both single bouts and repetitive bouts of exercise. Additionally, tryptophan supplementation may decrease agonistic behaviours, without having any effect on voluntary activity.
Highlights
Sled dogs are endurance athletes that perform high levels of repetitive aerobic and resistance exercise
There was a negative association between the duration of a bout of agonistic behaviours and week of training for dogs receiving Trp-supplementation (β = -0.32, 95% CI [-0.55, -0.09], R2 = 0.10, P = 0.007; Fig 1B); no association was observed for dogs receiving the control diet (β = -0.13, 95% CI [-0.41, 0.15], R2 = 0.01, P > 0.10; Fig 1A)
The findings of the current study suggest that Trp supplementation decreases agonistic behaviours in actively training sled dogs, while having no effect on activity or locomotion
Summary
Sled dogs are endurance athletes that perform high levels of repetitive aerobic and resistance exercise. Exercise-induced muscle fatigue, as well as overtraining, can lead to decreased mood and lack of motivation to exercise in humans [5]. In canines, these symptoms may manifest as behavioural changes, such as a reduction in locomotive behaviours prior to a bout of exercise, or a generalized decrease in voluntary daily activity. Voluntary activity consists of physical activity performed outside of scheduled training or racing bouts. There is a dearth of literature that defines how commonly implemented training regimens and repetitive bouts of exercise may impact the behaviour of performance dogs
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
