Situations that are emotional and arousing have an effect on cognitive performance. It is thought that beta adrenergic activation and the release of stress hormones enhance memory consolidation and lead to an increase in memorability of emotional events. This beneficial effect has been shown in humans, non-human primates and rodents. Techniques which could enhance memory for learning specific tasks would be highly valuable, especially in dogs, which are extensively trained to aid humans. A pseudo-randomized, counterbalanced, between subject study designs was utilised and 16 Labrador Retrievers ranging from 1 to 9 years of age were trained in a 2-choice discrimination paradigm. After task acquisition, either a playful activity intervention (N = 8) or a resting period (N = 8) took place, lasting for 30 min. A range of factors including age, sex, training experience and trials to criterion on each day was subjected to a multiple factor/covariate General Linear Model analysis. The results show that playful activity post-learning improved training performance evidenced by fewer trials needed to re-learn the task 24 h after initial acquisition (playful activity group: mean number of trials 26, SD 6; resting group: mean number of trials 43, SD 19, effect size 1.2). Average heart rate, as a measure of arousal, during the intervention was significantly higher in the playful activity group (143 beats/min, SD 16) versus the resting group (86 beats/min, SD 19, P < 0.001). Salivary cortisol did not significantly differ between groups during training, however a significant decrease (T: − 4.1 P < 0.01) was seen after the playful activity. To our knowledge this is the first evidence that posttraining activity may influence training performance in dogs.