Intraspecific attachment in domestic dogs (Canis familiaris): does it differ from young adults to adults?

Dogs are known to form strong relationships towards subjects of their own kind and of other species. This research assessed whether age affects intraspecific attachment bonds in female dogs. Fifteen female dogs participated in the study: 7 young adults (between 12 and 24 months of age) and 8 adults (more than 24 months old). Their behavior was analyzed in a modified version of the Ainsworth’s Strange Situation Test, consisting of seven 2-minute episodes in which the presumed attachment figure was played by a conspecific living in the same household. Two social behaviors (physical contact and proximity towards the other dog/stranger) and 5 non-social behaviors (exploration, locomotion, whining, staying close to the door, and behaviors directed to the door) were observed in all 7 episodes. The only statistically significant difference was found for whining when examined dogs were in complete isolation (episode 5). Young dogs whined more. Young adults spent marginally, but not significantly more time in physical contact with their cohabitant dog in some circumstances. These preliminary results suggest that, among female dogs, age slightly modified the attachment system and that this effect may be more pronounced in an unfamiliar environment and in the absence of the owner. Future research may better assess if and how age affects the intraspecific attachment in adult dogs.