Supporters of purebred dogs have been fighting a long battle against those who denounce such breeding as cruelly perpetuating genetic disorders that allegedly result in illness or deformities. Opponents of purebred dogs promote adoption or rescue of mixed-bred dogs instead of the purebred varieties.
Now, after scientists carefully compared the incidence of certain inherited traits in these two dog populations-purebred versus mixed-bred-there is finally a glimmer of truth into this long-debated topic.
As Carol Beuchat PhD reported, The Institute of Canine Biology Institute studied more than 27,000 dogs, comparing the incidence of 24 genetic disorders in mixed versus purebred dogs and found:
1) The incidence of 10 genetic disorders (42%) was significantly greater in purebred dogs. 2) The incidence of 1 disorder (ruptured cranial cruciate ligament; 4%) was greater in mixed breed dogs. 3) For the rest of the disorders examined, they found no difference in incidence between mixed and purebred dogs.
The scientists reviewed medical records, looking specifically for diagnoses of the following 24 genetic disorders:
hemangiosarcoma, lymphoma, mast cell tumor, osteosarcoma, aortic stenosis, dilated cardiomyopathy, hypertrophic cardiomyopathy, mitral valve dysplasia, patent ductus arteriosus, ventricular septal defect, hyperadrenocorticism, hypoadrenocorticism, hypothyroidism, elbow dysplasia, hip dysplasia, intervertebral disk disease, patellar luxation, ruptured cranial cruciate ligament, atopy or allergic dermatitis, bloat, cataracts, epilepsy, lens luxation, and portosystemic shunt. See Prevalence of inherited disorders among mixed-breed and purebred dogs: 27,254 cases (1995–2010), J Am Vet Med Assoc 2013;242:1549–1555.
No differences in expression of 13 genetic disorders were detected between purebred dogs and mixed-breed dogs (ie, hip dysplasia, hypo- and hyperadrenocorticism, cancers, lens luxation, and patellar luxation).
Looking ahead, animals scientists, theriogenologists (veterinarians with special training in animal reproduction), and breeders can use this information to help inform their breeding choices and select to reduced the prevalence of the disorders identified in certain breeds.
Of course, this study only analyzed genetic disorders that result in physical ailments. Most people interested in breeding, showing or purchasing a purebred dog are attracted to a particular breed for its behavioral characteristics, skill, or other specific attributes, in addition to their physical characteristics.
Breeders, working hand-in-hand with their veterinarians, will continue to improve upon both the physical and behavioral characteristic of each breed.
As provided on their websites, the American College of Theriogenologists and Society for Theriogenology stress the importance of purposeful breeding and both groups:
promote the breeding of healthy, genetically superior dogs to maintain a diverse canine population that meets the needs of society for companion dogs and working dogs. The College and Society support practices to promote optimal health of all breeding dogs. Purpose-bred dogs are maintained subject to regulation by institutional and government agencies, while similar guidelines for non-institutional breeders are lacking.
While the debate between purebred versus mixed-bred dog will undoubtedly continue, there is one thing we can all agree upon. Dogs are indeed our best friends.