Behaviour and welfare in relation to pathology § Donald Maurice Broom Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK Available online 28 December 2005 Abstract Behaviour is an important way of adapting to disease for individuals and selective pressures resulting from disease have had major consequences for the evolution of behaviour. Behaviour, adrenal and other physiological responses, immunological responses and brain activity all help in coping with disease. Health is an important part of welfare and any pathology implies some degree of poor welfare. Sickness behaviour and physiology are generally adaptive, involve interactions with the immune system and are partly mediated by cytokines. Since, firstly, an understanding of some behaviour requires knowledge of disease and, secondly, responses to disease and studies of brain and behaviour are helping to increase understanding of systems for combating disease, interdisciplinary co-operation is needed for the development of these areas of science. # 2005 Elsevier B.V. All rights reserved. Keywords: Pathology; Health; Welfare; Abnormal behaviour; Disease; Brain; Cytokine; Infection; Immune suppression; Sickness; Pleasure 1. Introduction The central topics to be considered in this paper are the ways in which behaviour, adrenal and other physiological responses, and brain activity change during disease. The first issues considered are some of the links between behaviour and health which have been reviewed in more detail elsewhere. There is confusion about the meaning of key concepts www.elsevier.com/locate/applanim Applied Animal Behaviour Science 97 (2006) 73–83 § This paper is part of the special issue entitled International Society for Applied Ethology Special Issue—A Selection of Papers from the 38th International Congress of the ISAE, Helsinki, Finland, August 2004, Guest edited by Victoria Sandilands and Carol Petherick. E-mail address: dmb16@cam.ac.uk. 0168-1591/$ – see front matter # 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.applanim.2005.11.019