Dog behavior in the Ainsworth Strange Situation Test during separation from the owner and from the cohabitant dog

Dogs are known to form strong relationships towards subjects of their own kind and of other species. The aim of this research was to compare dog behavior when separated from a human and a canine companion. Sixteen dogs (9 females and 7 males, 49.8 ± 54.3 month old, belonging to different breeds) were observed during the 2-minute isolation episode of the Ainsworth Strange Situation Test. Each dog was tested twice: once the dog was separated from the owner and once from a cohabitant dog. The duration of 19 behaviors was measured in both conditions and compared using the Mann-Whitney test (p<0.05). Proximity to the door (medians: 95.5 versus 54.5; Z=2.38; p=0.017), behaviors against the door (7.0 versus 0.0; Z=2.13; p=0.033), barking (0.0 versus 0.0; Z=2.37; p=0.017), and trying to escape from the experimental room (0.0 versus 0.0; Z=1.83; p=0.067) were statistically higher when dogs were separated from the conspecific compared to when separated from the owner; whilst passive behavior was higher when isolated from the owner (13.0 versus 0.0; Z=3.18; p=0.001). Results suggest that dogs showed a higher protest at separation when isolated from a cohabitant dog. Although it may be interpreted as a display of a higher intraspecific attachment, the higher stress may be due to the separation from the conspecific summed to a condition where the owner was not present. It is possible that multi-household dogs have less opportunities to be left alone and therefore to get used to isolation. Thus, it may have important consequences on dog welfare.