By Dr. Becker
If you’re a dog lover, you’re probably aware that many people feel mixed breeds are healthier than purebreds. One of the reasons for this notion is that when two or more breeds are blended together, there’s less risk a dog will inherit breed-specific diseases.
The idea that mutts are healthier makes a certain amount of sense when you consider the poor breeding practices of puppy mill operators and many AKC associated breeders as well. There’s excessive focus on breeding animals for certain physical characteristics, and entirely too little attention paid to selecting dogs for health and longevity.
The belief that breed-blending creates healthier dogs is part of the reason “designer dogs” like Goldendoodles, Morkies and Puggles have become so popular. It’s also why breeders are able to ask inflated prices for dogs that aren’t purebred.
But are mixed and designer breeds really healthier? Not according to what many veterinarians see in their practices... and not according to a recently published five-year study of veterinary cases at the University of California, Davis. This research indicates that mixed breeds don't automatically have an advantage when it comes to genetic disorders.
13 of 24 Genetic Disorders Occurred at Same Rate in Mixed Breeds and Purebreds
The UC Davis researchers looked at the records of over 90,000 purebred and mixed breed dogs that had been patients at the university’s veterinary medical teaching hospital between 1995 and 2010. Designer dogs were included in the study, since crossbreeding is presumed to reduce or eliminate genetic disorders like hypothyroidism, epilepsy, hip dysplasia and cancer.
Of the 90,000 records reviewed, 27,254 involved dogs with at least one of 24 genetic disorders, including various types of cancers, heart disease, endocrine system dysfunction, orthopedic conditions, allergies, bloat, cataracts, eye lens problems, epilepsy and liver disease.
According to the study, which was published in the June 1, 2013 edition of the Journal of the American Veterinary Medical Association1, the prevalence of 13 of the 24 genetic disorders was about the same for purebreds as mixed breeds. Some of those disorders were hip dysplasia, hyper- and hypoadrenocorticism, cancers, lens luxation and patellar luxation.
Ten conditions were found more frequently among purebred dogs, including dilated cardiomyopathy, elbow dysplasia, cataracts, and hypothyroidism.
One disorder was actually more common in mixed-breeds – cranial cruciate ligament ruptures.
“Overall, the study showed that the prevalence of these genetic disorders among purebred and mixed-breed dogs depends on the specific condition," said animal physiologist Anita Oberbauer, professor and chair of the Department of Animal Science at UC Davis and lead author of the study.
Breeds with Similar Lineage Share Gene Mutations for Inherited Diseases
The UC Davis study data also suggests breeds that share a similar lineage are more prone to certain inherited disorders. According to Phys.org:
“… four of the top five breeds affected with elbow dysplasia were the Bernese mountain dog, Newfoundland, mastiff and Rottweiler—all from the mastiff-like lineage. This suggests that these breeds share gene mutations for elbow dysplasia because they were descended from a common ancestor.”
The flip side of the coin is disorders that occur in both mixed breeds and purebreds seem to originate from well-established gene mutations that have spread throughout the dog population. These disorders include hip dysplasia, tumor-causing cancers, and hypertrophic cardiomyopathy.
18 Points to Discuss with a Breeder
If you’re thinking about purchasing a purebred puppy, I’ve developed a method to help you determine how healthy your new pet may be. Investigating the lifestyle of your prospective puppy’s parents through questions posed to the breeder can give you excellent insight into the health of your pup and his littermates.
These questions are intended to determine how committed the breeder is to the well-being of his or her dogs and their litters. If a breeder can’t or won’t answer these questions about the parents of the puppy you’re considering, I recommend you find another breeder.
Now add up the scores to assess the quality of your breeder:
81-90... Exceptional. With your commitment to maintaining the same level of care, puppies obtained from this breeder have the best chance for vibrant health and a long life.
71-80... Good. With your commitment to maintaining the same or a higher level of care, puppies from this breeder have a good chance of being healthy throughout life.
56-70... Above average. Puppies from this breeder will need all aspects of wellness addressed consistently to maintain balanced health.
36-55... Average. Puppies from this breeder may exhibit metabolic, skeletal or nutritional roadblocks that will take time, money and effort to address.
25-35... Below average. Puppies from this breeder will survive, but not likely thrive. Depending on your level of commitment, your puppy can have a good quality of life. Dogs in this category should not be bred; litters from parents that aren’t thriving, rarely thrive.
Under 25... Poor. Puppies from this breeder will survive, but not likely thrive. Depending on your level of commitment, your puppy can have a good quality of life. Dogs in this category should not be bred; litters from parents that aren’t thriving, rarely thrive.