Chronic stress in dogs subjected to social and spatial restriction. II. Hormonal and immunological responses

Two groups of beagles, accustomed to spacious group housing, were subjected to social and spatial restriction and studied for manifestations of chroni c stress with a time interval of 7 weeks between the groups. The change fro m outside group housing (the control period) to individual housing in small indoor kennels resulted in sustained decreases in urinary adrenaline/creat inine and noradrenaline/creatinine ratios for the total group. Urinary dopa mine/creatinine and noradrenaline/adrenaline ratios were statistically unaf fected. Socially and spatially restricted dogs that had experienced pleasan t weather during the control period showed (a) increased salivary and urina ry cortisol concentrations, (b) a diminished responsiveness of the pituitar y-adrenal axis to a sudden sound blast or exogenous CRH, (c) intact plasma ACTH and cortisol suppressions after dexamethasone administration, and (d) increased concanavalin A induced lymphocyte proliferations. When social and spatial restriction was preceded by a control period during which the weat her was bad, these physiological responses were either augmented (lymphocyt e proliferation), or offset (salivary and urinary cortisol), or directed op positely (CRH-induced ACTH and cortisol responses). Together with the previ ously presented behavioral observations, these data suggest that bad weathe r conditions during spacious outdoor group housing induced early stress tha t attenuated the negative appraisal of the subsequent period of social and spacial restriction. In comparison to male dogs, bitches showed increased H PA responses to a sound blast or exogenous CRH. Their increased attenuation s of the ACTH and cortisol responses to CRH after 5 weeks of restricted hou sing indicates that bitches are not only more susceptible to acute stress, but also to chronic housing stress. It is concluded that the quality of cir cumstances preceding a period of affected well-being determines the magnitu de and even the direction of the behavioral and physiological stress respon ses. Basal salivary and urinary cortisol measurements are useful for the as sessment of chronic stress, and of poor welfare in dogs. The use of urinary catecholamine, peripheral leucocyte, and lymphocyte proliferation measures requires further investigation. (C) 1999 Elsevier Science Inc.