Should I whine or should I bark? Qualitative and quantitative differences between the vocalizations of dogs with and without separation-related symptoms

Separation-related disorder (SRD) is one of the most common behavioral problems of companion dogs, causing inconvenience and stress for dog owners and others living close by, as well as being considered as a major contributor to poor animal welfare. Although excessive vocalization is considered as one of the typical symptoms of SRD, until now there were no attempts to analyze and compare the vocal output of affected and non-affected dogs in a systematic, empirical test. In a three-stage outdoor separation experiment we investigated the vocal response of 25 family dogs with, and 20 family dogs without, owner-reported SRD symptoms to the (1) departure; (2) absence; and (3) return of the owner. After the analysis of the occurrence and onset latency of barks and whines, we found that contrary to the commonly held view of excessive barking being one of the trademarks of SRD, dogs with owner-reported SRD symptoms can be reliably characterized by the early onset and high occurrence of whines during the departure and 2 min long absence of the owner, while barks were affected mainly by the age of the dogs. Breed and neuter status may modify the vocal reaction to separation, we found that more purebred dogs barked sooner, while breed and neutering status affected the whines only during the departure of the owner, showing that more mixed breeds and intact dogs whined in this phase. This is the first study that targeted directly the vocal response of family dogs to separation from the owner, and according to the results, whines and barks reflect potentially different motivational/inner states of dogs during a short isolation episode. Although the effect of other factors, such as sex, neuter status and breed cannot be ignored, the owner reported SRD status of dogs showed a high coincidence with the early onset of whining, which in turn proved to be a good indicator of high stress levels of dogs in this situation.