Approximately 41 % of dogs in the UK are described by their owners as pedigrees (J. T. Murray unpublished telephone survey). Many such dogs are far from healthy, as has been highlighted both by the popular media (e.g. BBC 2008) and in a range of reports, reviews, and scientific papers. Breeding dogs primarily for their appearance has led to compromised health and welfare in two different ways, one resulting directly from selection for exaggerated physical features and the other, indirectly resulting in an increased incidence of disease (see also Duffy and Serpell, this volume).
Exaggerated Physical Features
Artificial selection has resulted in a wide variety of morphologies in different breeds of dog. Many breeds are anatomically modified in ways which compromise their physical health. The English bulldog is a regularly cited example of morphological extremes, resulting in locomotion difficulties, breathing problems, and an inability to mate or give birth without physical and/or surgical interventions (Advocates for Animals 2006). However, there are many other less visually obvious anatomical deformities in other breeds, ranging from overly long backs to heavily wrinkled skin, and flat faces that restrict breathing.
Systematic studies have started to investigate the effects of these breed modifications. For example, Brachycephalic Obstructive Airway Syndrome (BOAS) has been shown to have detrimental effects on health, and syringomyelia causes significant pain to Cavalier King Charles Spaniels) making it clear that breeding dogs with such traits affects not merely their health and longevity but also psychological well-being. Effects on the dogs’ capacity to behave normally are less frequently mentioned. Severely reduced limb lengths, for example, may restrict the ability of dwarf dogs to run freely, and breeds with respiratory deformities (e.g. brachycephalic breeds) may be prevented from running without shortness of breath. Their ability to explore and exercise is compromised, and their opportunity for social interactions limited, which likely restricts their socialisation and thus potentially further restricts natural behaviour and diminishes their quality of life.
Numerous breeds are also anatomically modified such that their capacity to signal is drastically reduced: stiff legs prevent adjustments of height; brachycephalic breeds are less able to utilise facial expressions; dogs with very short or curled tails, or with immobile drooping or erect ears lose the function of important signalling structures. Short permanently erect fur leaves dogs unable to raise their hackles, whilst long or dense fur can obscure much body language communication. Short legs and long bodies not only prevent proper locomotion, they may also prevent a dog from play-bowing to invite playful interactions with other dogs. Play behaviour is rewarding and is important for normal social development, and high play levels are an indicator of positive welfare. Since play signalling is critical to the initiation and continuation of dog play, and can prevent interaction escalating into aggression, this is also a potential welfare concern.
Increased Incidence of Inherited Disease
Selective breeding primarily for appearance has also led to dog breeds becoming especially susceptible to a whole suite of disorders, many of which are acutely painful or chronically debilitating. This is a result of reduced genetic diversity, coupled with ill-advised breeding practices (whereby breeders inadvertently select regions of the genome which happen to contain a disorder as well as the trait they desire), and insufficient selection pressure on health and welfare. The inherited diseases are wide-ranging and include cardiac disease, eye disease, diabetes, glaucoma, and congenital sub-aortic stenosis. In a review of fifty UK dog breeds, every breed suffered from at least one of the 312 inherited disorders catalogued, with the nervous system the most commonly affected organ, pointing to potential effects on psychological well-being that are not yet fully explored.
Selective breeding practices are also likely to impact on behaviour indirectly, since basing breeding choices primarily on physical appearance means attention is diverted away from temperament. Studies reporting breed differences in the incidence of behaviour problems abound, but interpretation of these differences is not always straightforward. Some of these may be a consequence of selective breeding: For example, there is evidence for a genetic predisposition toward aggression in some lines of golden retrievers. Behaviour described as ‘‘dominant-aggressive’’ varies greatly between differently coloured cocker spaniels, and Duffy et al. found that show-lines of English Springer spaniels were more aggressive to humans and other dogs than were lines bred for work in the field. More generally, Svartberg compared 13,097 Swedish dogs of 31 breeds, and found that dogs bred for working were less likely to display social and non-social fearfulness, and were more playful and curious, than dogs from show lines. Caution is needed when interpreting such differences, since it is generally impossible to tease apart the consequences of selective breeding from differences in the way breeds (and especially lines within breeds) are reared. However, since most pedigree dogs live the majority of their lives as household pets, and behavioural disorders can both be a consequence of negative affective states and can also result in dogs being surrendered or euthanized, selective breeding remains a significant welfare issue.
Why Do Such Effects Persist?
It is difficult to comprehend how breeders and purchasers could condone and even perpetuate such problems. When studying BOAS, Packer et al. (2012) recorded that despite over two-thirds of owners of affected dogs reporting daily breathing difficulties in their dogs during exercise, 58 % stated that their animal did not currently, or had ever had a breathing ‘‘problem’’. This suggests that most owners do not recognise breathing difficulties as a welfare issue for the dog, perhaps because they rely on a narrow definition of welfare, in which provided they see no obvious signs of pain, then behavioural and mood effects can be ignored. In recent years, breeding associations (e.g. UK Kennel Club) have started both to encourage testing for and breeding to eliminate inherited diseases, and also to alter some breed standards to dissuade breeders from selecting for the most extreme and obviously debilitating conformations. However, since all fifty of the most popular breeds have at least one aspect of their conformation that predisposes them to one or more disorder (and there is no reason to assume the remaining 250-plus breeds are not similarly affected), many would argue that more needs to be done in order to prevent suffering (EFRA 2013). Undoubtedly, education of owners as well as breeders is still required.