Prospective pet owners and policy makers would like to be able to predict the probable future behavior of dogs in order to choose appropriate companion dogs and to anticipate problematic behaviors such as aggression toward humans. Such predictions are commonly made based on presumed breed characteristics, both in the case of purebred and mixed-breed dogs. These predictions rest on three main assumptions: that dogs are readily identifiable as members of a particular breed; that behavior can be reliably predicted according to breed; and that the behaviors associated with specific breeds are relevant to the contemporary function of most domestic dogs as companions for human families. The purpose of this paper is to examine these assumptions in order to determine whether a breed label is a useful indicator of the suitability of a companion dog.


People often expect certain behaviors from a purebred dog, believing that its forebears 'have been bred for centuries" to hunt or guard or fight or herd (fill in any common behavior). This is simply not the case with modem dogs. First, the
lineages of modem registered breeds are very recent, with most dating back only decades. The 'bred for centuries' idea does not apply. Second and more importantly, in the relatively short period since there have been standardized
selection criteria for purebred dogs, those criteria have dated exclusively to appearance, not to behavior. Breed standards will sometimes give lip service to desired temperament but these qualities are never defined in a way that can be applied by a judge to the dog in a show ring. Because purebred dogs are judged entirely by how they look, morphological qualities are what breeders select for. There are breeders who specialize in dogs bred for specific competitions, such as hunting and herding, where the concern is for performance rather than appearance, but these dogs almost certainly represent a small subset of the purebred population. One recent study of purebred dogs in Sweden confirms that the emphasis on breeding for appearance has all but erased any behavioral selection that existed in the past, and this study included members of the breeds that were still being used in working dog trials of various kinds!

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