Epidemiology of Disorders Compromising the Welfare of Dogs and Cats

Abstract

Real-world animal welfare problems in dogs and cats require the application of epidemiological methods in animal welfare science. This thesis aimed to (a) investigate the epidemiology of cat overweight and obesity (O&O), (b) explore the trends in dog body shape, and (c) generate a novel metric, Welfare-Adjusted Life Years (WALY), to quantify impaired welfare caused by disorders in dogs and cats. Observational studies were conducted with data collected from multiple sources. Statistical models identified and quantified the risk factors for feline body condition score (BCS) as well as investigated the effect of BCS on survival, longevity and 21 health conditions in cats. Trends in the average height, size and head shape in Australian pedigree dogs were explored. The concept and the method of the WALY were developed and demonstrated with 10 canine diseases. The WALY of a disorder was defined as the sum of the years lived with impaired welfare caused by the disorder and the years of life lost due to the same disorder. Many risk factors for feline O&O, including the behaviour of begging for food, townhouse dwelling and owners holding a neutral or agreeing attitude towards feline O&O, were identified for the first time. This is the first study reporting the associations of O&O with atopic dermatitis, hypertension, asthma, diarrhoea, ophthalmic conditions and allergic conditions in cats. BCSs of ≤5 and of 9 shortened the survival and lifespan in cats. A reduction in size and flattening of the face of Australian pedigree dogs was observed over time. Of the 10 canine diseases examined, thoracolumbar intervertebral disc disease and atopic dermatitis had the lowest and highest WALYs at 2.83 and 9.73, respectively. This thesis examined the welfare-related epidemiology of single and multiple disorders. The WALY metric offers a whole new perspective to measuring welfare compromise in dogs and cats and has extensive applications.