Sessions

The evolutionary role of emotions is to help organisms respond adaptively to various challenges by promoting the search for rewards and resources and avoiding dangers, thereby ensuring survival. Emotions influence behavior, which in turn can function as a communicative signal, reflecting an individual's intentions, traits and also internal state. Morphology can also affect these signals, but the combined influence of emotional state and morphology remains poorly understood. Due to their morphological diversity, dogs offer a suitable model for studying this interaction. Canine vocalizations reflect both emotional states and physical traits, making them a valuable tool for assessing welfare. Moreover, in brachycephalic (short-headed) breeds, extreme morphology is associated with serious health and communication issues, raising welfare concerns. Thus, we aimed to investigate how different vocalization types vary across emotional contexts in dogs and how these are influenced by extreme head morphology. We studied 39 dogs of varying head shapes under laboratory conditions. So far, we have annotated the vocal behavior of 28 dogs and analysed acoustically the vocalizations of 16 of them. We exposed dogs to five emotional contexts: on the first day, exploration (neutral control), play (positive), and indoor separation (distress); and on the second day, exploration (neutral control), a threatening stranger (agonistic), and petting (positive). We coded the types and durations of vocalizations, and analyzed their acoustic features: pitch (center of gravity frequency) and noisiness (Wiener entropy). Although all vocal types appeared in most contexts, their occurrence varied significantly. While panting was common in all situations, whines and whistle whines were especially frequent in distress contexts. In contrast, barks, woofs, and growls were primarily associated with agonistic contexts, whereas grunts were more typical of positive situations. We found significant interactions between vocal type, context, head morphology, and body weight in terms of pitch. Agonistic barks and growls had the lowest pitch, and shorter muzzles were associated with higher-pitched vocalizations in some cases. Interestingly, body weight had opposing effects on whines and whistle whines, likely due to differences in vocal production mechanisms. Vocalizations were clearest in the agonistic context and the noisiest in the distress context. Furthermore, brachycephalic dogs produced clearer whistle whines, but noisier other vocalizations, while larger dogs – especially in agonistic and neutral situations – produced cleaner sounds, including growls, pants, and whines. Our findings demonstrate that emotional context and head morphology significantly influence the acoustic characteristics of canine vocalizations. Identifying distinct vocal types and analyzing their key acoustic parameters may provide a promising tool for the objective assessment of dogs' welfare and emotional states.