Most Pitbulls Are Mixed-Breed Dogs

A recent in-depth study analyzing the DNA of shelter dogs found that most dogs with DNA from breeds included in the pitbull-type category are mixed-breed dogs. This study involved testing the DNA of 919 dogs, discovering that among the 249 dogs with pitbull-type ancestry, 98% were mixed-breed dogs, with only 2% being purebred. Furthermore, it revealed that more than half of the dogs with pitbull-type ancestry had less than a 50% DNA match with any breeds included in the pitbull-type category and are therefore, by definition, mixed-breed dogs. Usually, a dog needs more than a 50% DNA match with a specific breed to be considered a mix of that breed. For example, a 'Boxer mix' would predominantly have Boxer DNA or at least 50% DNA from Boxer ancestry. If a dog doesn't meet this threshold, it is considered a mixed breed without any breed-specific labels. Consequently, this study determined that most dogs labeled as 'pitbulls' don't qualify as 'pitbulls' or 'pitbull mixes' since they have less than 50% pitbull-type DNA or another breed predominates their genetic makeup. These findings have significant implications for dog bite statistics, medical studies on dog bites, media reports on dog bites, and for breed-specific legislation (BSL).

DNA Results of 249 PiTbull-Type Dogs 📑

Impact On Dog Bite Statistics and BSL 📊

The findings from this study hold significant implications for how dog bite-related breed data is used across various contexts, including dog bite statistics, medical research on dog bites, media reporting on such incidents, and breed-specific legislation (BSL). Typically, BSL affects dogs identified as pitbull-types based on having more than a 50% DNA concentration of pitbull-type ancestry. However, this study suggests that more than half dogs classified as pitbull-types would not be impacted by BSL, if challenged by their owner with DNA evidence. Moreover, another study found that, on average, 60% of dogs visually identified as 'pitbulls' lacked DNA from any pitbull-type breeds, further challenging the accuracy of breed identification in media reports and the validity of breed-specific data in dog bite statistics and in medical studies on dog bites.

These findings underscore the unreliability of breed identification based on appearance and in media reporting, which often contributes to misleading and flawed statistics and problematic medical studies on dog bites. The prevalent use of inaccurate breed information from media reports exacerbates this issue, leading to a distorted view of the breeds involved in bite incidents. Given these discrepancies, there is a strong case for mandating DNA testing for dogs involved in serious bite incidents. Such a measure would clarify that the majority of these cases do not involve pitbull-type dogs but are instead linked to mixed breeds or other breeds altogether.

The complexities of accurately identifying a dog's breed are well-known. However, the evidence suggests that using DNA to determine a dog's breed—whether for dogs impacted by BSL due to their appearance, for dog bite-related incidents, or to support data in dog bite statistics—may indeed be the greatest weakness of BSL.

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Last Updated

4/12/2024