BEHAVIORAL, SALIVA CORTISOL AND HEART-RATE RESPONSES TO DIFFERENT TYPES OF STIMULI IN DOGS

Stress parameters that can be measured noninvasively may help to ident ify poor welfare in dogs that live in private homes and institutions. Behavioural parameters are potentially useful to identify stress, but require further investigation to establish which behaviours are approp riate. In the present study, behaviours were recorded and analysed for signs of acute stress in dogs. Simultaneously, saliva cortisol and he art rate were measured to support the interpretation of the behavioura l data with regard to stress. Ten dogs of either sex, different ages a nd various breeds were each subjected to six different stimuli: sound blasts, short electric shocks, a falling bag, an opening umbrella and two forms of restraint. Each type of stimulus had been selected for it s assumed aversive properties and was administered intermittently for 1 min. The stimuli that could not be anticipated by the dogs, sound bl asts, shocks and a falling bag, tended to induce saliva cortisol respo nses and a very low posture. The remainder of the stimuli, which were administered by the experimenter visibly to the dog, did not change th e cortisol levels but did induce restlessness, a moderate lowering of the posture, body shaking, oral behaviours, and to a lesser extent, ya wning and open mouth. Pronounced increases in the heart rate were nons pecifically induced by each type of stimulus. Heart rate levels normal ized within 8 min after stressor administration had stopped. Saliva co rtisol levels decreased to normal within the hour. Correlations betwee n behavioural and physiological stress parameters were not significant . From the present results, we conclude that in dogs a very low postur e may indicate intense acute stress since dogs show a very low posture concomitant with saliva cortisol responses. Dogs may typically show i ncreased restlessness, oral behaviours, yawning, open mouth and a mode rate lowering of the posture when they experienced moderate stress in a social setting. The nonspecific character of canine heart rate respo nses complicates its interpretation with regard to acute stress. (C) 1 998 Elsevier Science B.V. All rights reserved.