An oblong head, well-arched toes, a broad chest, and nostrils tilted downward at the tip – what could be more attractive? This is the epitome of beauty for Bull Terriers, at least according to dog show standards. 

Yet, the inner workings of purebred dogs may not be quite as exquisite as their glossy fur suggests. Heart disease, kidney disease, and neurological diseases (including obsessive compulsive tail-chasing) plague purebreds of this breed. 

Issues such as these are not just relegated to Bull Terriers, either. In general, purebreds are considered at a high-risk for health problems due to a lack of genetic diversity that results in inherited disorders. 

Inbreeding dogs as showpieces, rather than as an exemplar of health, can lead to some pretty grim complications. For example, half of all cavalier King Charles spaniels by the age of 5 will develop heart mitral valve disease (MVD), which is the breed's leading cause of death. The perfect flat, wrinkled face of a pug can lead to severe obstructions in breathing, and for large, ill-proportioned dog breeds, debilitating hip and elbow dysplasia are common even at a young age. 

As this video from Business Insider reveals, sometimes the best in show is not the best in health.

[H/T: Dog Behavior Science]