In the UK, numerous pedigree dogs of many breeds experience compromised welfare due to the direct and indirect effects of selective breeding. Many breeds are selected to have physical conformations which, although perceived by some to be desirable, have direct negative effects upon their welfare. Dogs are regularly bred whose heads are too large and pelvises too small to birth naturally or whose faces are so flat that they are unable to breathe or exercise normally. There are also many indirect effects of selective breeding for appearance, including significantly elevated prevalence of specific diseases within particular breeds. Current breeding practices can therefore result in unnecessary suffering due to pain, disability, disease and behavioural problems. In this paper, we summarise and review the current scientific evidence for such suffering, and difficulties associated with assessing the impact of current breeding practices. Limited record-keeping, lack of transparency in the breeding and showing world, and the absence of sufficient research, mean that the full extent of the problem is difficult to assess. Furthermore, the collection of data is currently unsystematic, and although there are specific case studies of individual breeds and particular disorders, relatively few have been conducted in the UK. Individual breeds each suffer from their own array of problems, so each breed's survival and improvement (in terms of health and welfare) is likely to require a different specific course of action. With 209 breeds currently registered in the UK, this makes the situation complex. We collate and present a range of suggestions which may help to improve pedigree dog welfare significantly, and prioritise these based on expert opinion.

The breeding of domestic dogs for dog fighting has resulted in numerous genetic alterations in a breed widely acknowledged to be the most successful fighting dog: the American Pit Bull Terrier (APBT). Much of the genetic foundation underlying the motivation and ability for pit fighting can be traced back to the earliest use of dogs for hunting purposes and continued through the selective breeding for use of dogs in wars and bull and bear baiting. In the development of the APBT as a fighting dog, there were two main breeding criteria. The first was, and remains, fighting success. The trait most prized by breeders of fighting dogs and considered most contributory to fighting success is ‘gameness’, which is the perseverance at a task even under extreme adversity, such as injury, pain, or fatigue. The second criterion was the absence of human-directed aggression. Since dogs are handled extensively before, during, and after the fights, dogs that showed aggression toward humans were eliminated from the gene pool. Indeed, anecdotal reports suggest that breeding may have been carried beyond that of simply selecting against human aggressiveness to a degree of enhanced affinity for humans. The result is that today's fight-bred APBT is genetically predisposed — but not predestined — to aggressiveness toward other dogs and a strong social attraction to humans. The human affinity trait is a highly valuable characteristic that ought to be preserved. With the appropriate breeding decisions, the power of genetic selection suggests that this goal, along with normalising the genetic disposition for conspecific aggressive tendencies, should be ultimately achievable.