Chronic stress in dogs subjected to social and spatial restriction. I. Behavioral responses

Six weeks of social and spatial restriction were used as a model to induce chronic stress in Beagles. Behavioral and physiological measurements were p erformed during a period of enriched spacious outdoor housing in groups (GH ) and during a subsequent period of solitary housing in small indoor kennel s (IH). Behavioral parameters that may indicate chronic stress in dogs are reported. During IH, the dogs showed significantly (comparison-wise error r ate <0.05) lower postures than during GH. IH induced enduring increments in frequencies of autogrooming, paw lifting, and vocalizing, and was associat ed with incidents of coprophagy and repetitive behavior. So far, we interpr et the behavioral changes as signs of chronic stress. Relatively low levels of walking, digging, intentions to change from one state of locomotion to another, and increments in circling are conceived as obvious adaptations to the specific features of the IH system. By challenging the dogs outside th eir home kennel we tested whether the dogs' coping abilities were affected by IH. Dogs that were challenged were introduced into a novel environment, given the opportunity to escape from their home kennel, restrained, walked down an unfamiliar corridor, presented a novel object, exposed to loud nois e, given food, or confronted with a conspecific. During IH, challenged dogs exhibited higher postures, showed more tail wagging, nosing, circling, uri nating, and defecating, and changed more often from one state of locomotion (or posture) to another than during GH. These behavioral changes were obse rved across the different types of challenges, with the exception of the no ise administration test. In the presence of conspecifics, the socially and spatially restricted male dogs behaved more dominantly and aggressive than during the time that they were kept in groups. Such behavior manifested as increased performances of raised hairs, growling, paw laying, and standing over. Both sexes showed increases in paw lifting, body shaking, ambivalent postures, intentions to change from one state of locomotion to another, and trembling in any of the challenges, excluding the walking down the corrido r test. In short, during a variety of challenges, socially and spatially re stricted dogs exhibited a heightened state of aggression, excitement, and u ncertainty. Behavioral differences between dogs that had experienced pleasa nt and bad weather conditions during GH, suggested that "pleasant-weather i ndividuals" had experienced early stress during the control period, and, as a result, responded to the subsequent period of IH differently. Regardless of the housing conditions, challenged bitches showed stronger indications of acute stress than male dogs. Gender did not affect the chronic stress re sponses to social and spatial restriction. A low posture and increased auto grooming, paw lifting, vocalizing, repetitive behavior, and coprophagy may indicate chronic stress in dogs, and as such, can help to identify poor wel fare. When challenged, chronically stressed dogs may show increased excitem ent, aggression, and uncertainty, but the nonspecificity of such emotional behavior will complicate its practical use with regard to the assessment of stress. (C) 1999 Elsevier Science Inc.