Think mutts are less likely to have genetic issues than purebreds? Well, think again. In a study published in the June 1 Journal of American Veterinary Medical Association (JAVMA) researchers studied the medical records of 62,750 dogs diagnosed with genetic disorders during a 15 year period.
The study, titled, Prevalence of inherited disorders among mixed-breed and purebred dogs: 27,254 cases (1995–2010), Studied prevalence of 24 genetic disorders in the population. Thirteen genetic disorders to be found in equal measure in both pure bred and mixed-breed dogs. Included in those thirteen disorders were hip dysplasia, addisons, Cushings Diseases, various cancers and patellar luxation.
Ten disorders were found to be more common in purebred dogs, these disorders include dilated cardiomyopathy, elbow dysplasia cataracts and hypothyroidism. For thirteen disorders, including hip dysplasia, Cushing's disease, cancers, luxating patellas, purebred dogs had no higher incidence than did mixed breed dogs. Mixed breed dogs had a higher prevalence of cranial cruciate ligament (CCL) tears than did purebred dogs.
According to the researchers, the study illustrates that for most heritable diseases mixed breeds confer no greater over all health. Heritable diseases clearly run in some pure bred lines, however according to the researchers, thirteen of the 24 diseases studied were present across the entire canine population prior to breeding for specific traits, and are therefore just as likely to show up in a mixed breed dog as a purebred.
Not mentioned in the research is that for many purebred dogs genetic tests are available for breeders to help them eliminate certain heritable diseases from the line. This option is highly unlikely to examined in a mixed dog breeding as these are often accidental.
Heritable diseases can be devastating for pet owners, knowing the history of a dog's lineage may provide a buffer against some of these issues. In-breeding has certainly led some breeds to have a high incidence for some diseases, and mixed derived from that breed can suffer from the same set of issues.
Mutts can be fantastic companions, but do not expect them to cost less or live longer than a similar sized purebred.
Access to this study is available only through JAVMA membership, or can be purchased from JAVMA. An abstract is available here.