Employing epidemiological approaches to animal welfare problems: a treatise

From the point of view of an animal welfare scientist, animal welfare science is seen as transdisciplinary as it establishes a conceptual framework, using disciplines shared by other scientists (e.g. physiology, anatomy, behaviour, nutrition and pathology). From the point of view of other scientists, animal welfare is interdisciplinary as other scientists collaborate in the field, bringing expertise in their disciplines. This thesis aims to contribute to knowledge by demonstrating the benefit of applying a coherent framework of epidemiological standard techniques, to address a variety of animal welfare issues. The objectives are: 1 - to explore the different epidemiological study designs and biostatistical approaches and put them in an animal welfare scientific context, developing a coherent framework of useful standard techniques; 2 - to identify, discuss and assess novel animal welfare risk factors in a full range of animal settings: production, captive, companion and equine. The potential offered by different epidemiological study designs and analytical procedures is explored and put in an animal welfare context. The illustration of this integration is made using the submitted papers and therefore the methodologies used therein are discussed and justified. The full range of epidemiological study designs is used with the application of several biostatistical approaches. This fulfils the first objective of this thesis. The identification of different types of risk factors posed to animal welfare (genetic, environmental, husbandry and management) is one of the advantages in the use of epidemiological approaches to research animal welfare science. The identification and discussion of risk factors in a range of species (farm, companion, equine and captive) after the research contained in the publications submitted with this thesis, fulfils the second objective of this thesis. Other advantages in the use of epidemiological approaches to research animal welfare science are also discussed: introduction of standardised procedures allowing further studies; use of complex and real animal settings outside the laboratory environment; and contributions to animal welfare assessment.