Friendship or Competition? Symmetry in Social Play within the Two Packs of German Shepherd Puppies

SIMPLE SUMMARY: Social interactions within canine groups have been studied for decades. In relation to egalitarianism in social play (the “rule of 50:50”), most discussed attributes were body size or age of the play participants. We observed the social play of 14 German Shepherd puppies (two litters) at the age of 7 weeks, and once again at the age of 9 weeks (in total we observed 43 play pairs, also known as dyads). These litters were observed separately (litter 1: n = 28, litter 2: n = 15), and we evaluated 2542 interactions of social play in total. This total number included all interactions observed between the 43 dyads—1287 interactions at the age of 7 weeks old and 1255 interactions at 9 weeks old were recorded. The aim of our study was to evaluate symmetry within play interactions of puppies. Symmetry within the play has been confirmed for litter 1 at the age of 7 and 9 weeks and for litter 2 at the age of 7 weeks, but the final interpretation of our results is limited due to the small sample size and it is impossible to generalize our results for domestic dogs or a specific breed. For further studies, we would suggest an evaluation of breed differences (and including more individuals of each breed), ecological backgrounds and environmental factors regarding the development of egalitarian (or some other) play style. ABSTRACT: The symmetry of social play in Canids has been previously studied, especially in wolves, free-ranging dogs, and within mixed-aged groups, however our study focused on symmetry and asymmetry within play interactions in two litters (14 puppies) of German Shepherd dogs (GSDs). At the age of 7 weeks, we evaluated 1287 dyadic interactions (litter 1: n = 339 interactions, litter 2: n = 948 interactions), and at the age of 9 weeks we evaluated 1255 dyadic interactions (litter 1: n = 433 interactions, litter 2: n = 822 interactions). Dyadic interactions were observed and the winning indexes were calculated for 43 pairs (dyads). The groups of puppies studied were all the same age, therefore we focused on the aspects of sex and body size as primary variables. The weight and chest circumference of all puppies were measured. The distribution of interactions showed a slight inclination to mixed-sex dyads, but we did not obtain any statistically significant results concerning the impact of body size on play interactions. Symmetry in play was observed within litter 1 at the age of 7 weeks and at the age of 9 weeks, and within litter 2 at the age of 7 weeks. Since the number of puppies in this study was too small, these results should be interpreted regarding this limitation, and cannot be generalized to a larger population of domestic dogs nor the GSD breed. In further studies, it would be interesting to compare larger samples of different breeds, under different breeding conditions, and the effect of the environment on the style of social play.