Dr Patrick Mahaney Explores the Mixed Breed Health Myth in Observance of National Mutt Day

December 2, 2011

Photo of Sergio Donald Brown ArtistThis article appeared on petMD as part of Dr Mahaney’s The Daily Vet series.

In commemoration of National Mutt Day, I am exploring the notion that mixed breed dogs have health advantages over pure breeds.

What exactly makes a mutt? “Mutt” is a term typically referring to dogs, but does not necessarily exclude animal counterparts of other species. The term mutt is often used in a derogatory fashion, but it should be perceived in a more positive light. A mutt is merely a living being having a mix of known or unknown genetics. One can even consider most humans to be mutts due to our various genealogical lineages. Heck, I’m a French, Irish, and Lithuanian mutt.

Not all canines fit into the mutt category, as some dogs have specific genetic lineage that is traceable through generations and are thereby known as pure breeds. The American Kennel Club (AKC) defines purebred as a “dog whose sire and dam belong to the same breed and who are themselves of unmixed descent since recognition of the breed.”

As a practicing veterinarian I am aware of the commonly held perspective that mutts are healthier than pure breed dogs. There are some aspects of this statement that I agree with and others with which I disagree.

From a clinical perspective, what may make a mutt healthier is the general lack of awareness of specific illnesses that develop based on their genetics. Veterinarians can cite specific examples of pure breed dogs and rattle off a list of breed specific diseases; plus one for the mutts.

Veterinarians can never certify that a mixed breed dog will completely lack the potential for developing a genetically correlated disease. We can only speculate that a mutt may have a reduced likelihood as compared to a particular pure breed; minus one half for the mutts.

An example of this mixed versus pure breed phenomena is hip dysplasia (HD), one of the most common canine orthopedic abnormalities. HD (AKA Coxofemoral subluxation) is a developmental malformation of the hip joint that highly correlates with the genetics of many large dogs. HD is an undesirable trait, as it increases the likelihood that a dog will suffer from painful osteoarthritis during its lifetime.

Acquiring a dog from a reputable breeder who uses Penn HIP or Orthopedic Foundation for Animals (OFA) techniques to evaluate the sire and dam’s hip health can reduce the likelihood that the offspring of normal parents will develop hip dysplasia.

Breeds of dogs that are prone to hip dysplasia include (but are not limited to) the Golden and Labrador Retriever, Rottweiler, and German Shepherd Dog. Not every dog within these pedigrees has HD, yet plenty of mixes of these and other breeds do.

As compared to a dog’s breed, a more realistic determining factor of the likelihood of developing HD is physical size. Generally, large dogs (roughly > 50 lbs) are more likely to develop hip dysplasia than small dogs (say < 20 lbs), regardless of being a pure or mixed breed. Additional factors that play a role in a dog’s development of HD are: Fast rate of weight gain Obesity (see Pet Obesity: Health Implications, Recognition, and Weight Management)
Elevated protein, calcium, and other nutritional factors
Traumatic joint injury

Although acquiring a dog of prime and known genetic stock may reduce the likelihood that a disease like HD will develop, the overall picture of health and wellness is multifactorial. Both pure and mixed breeds have the same potential to develop illness secondary to toxic exposure or infection. Additionally, getting hit by car, enduring a dog fight, falling from heights, and other traumas have no mixed versus pure breed discriminatory pattern.

I am all for adopting a pet, provided you have adequate time, financial resources, and have made this decision in a well thought out manner. Organizations like PetFinder are leading the way in the on-line adoptive realm and are currently striving to place nearly 200,000 dogs into homes.

Interestingly, PetFinder lists the available canines by known or suspected breed categories. A disclaimer reads:

Breed Note: Many of these pets are mixes. In these cases, the breed listed is the one that best matches their looks and personality. Also, some of the pets presumed to be mixes may be purebred.

Perhaps claiming a dog is a particular breed makes it more adoptable after all.

Truly, I hope your mutt, pure breed dog, cat, or other companion animal lives many years having a great quality of life. Providing the best pet parenting possible, along with some good fortune, can help make this goal a reality.

Photo Credit: Donald Brown “Sergio”

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Copyright of this article (2011) is owned by Dr. Patrick Mahaney, Veterinarian and Certified Veterinary Acupuncturist. Republishing any portion of this article must first be authorized by Dr. Patrick Mahaney. Requests for republishing must be approved by Dr. Patrick Mahaney and received in written format.

{ 4 comments… read them below or add one }

Tegan December 3, 2011 at 2:01 PM

Thank-you for posting this. I think pure bred dogs get a bad rap in this department. I much rather get a purebred Labrador who has parents screened for hip dysplasia, than get a mixed breed puppy and ‘hope’ the parents were healthy stock. In reality, ethical breeders of purebreds are much more likely to breed healthy dogs than any cross bred combination.

TheOldBroad December 4, 2011 at 6:34 AM

Purely bred animals seems to be a much larger concern for dog people as opposed to cat people although there are many feline breeders. If one is looking for certain traits such as couch potato versus a high energy dog or a breed that’s good with children, it’s wise to take the dog’s breed into consideration.

Cats are pretty much cats. There isn’t a chance they’re going to grow to be 80 pounds or the size of a small pony. Most don’t need to be socialized so they can play at parks (like dog parks).

However, for those who fancy purebred cats, there are things of which to be aware for certain breed. For instance, I believe Burmese might have a tendency to cherry eye.

I have always had muttigree cats. There have been a variety of health issues from CRF (chronic renal failure) to hyperthyroidism to cancer. I currently have one with a congenital heart problem, HOCM (hypertrophic obstructive cardiomyopathy).

I wouldn’t change a single decision to add each to my household.

Patrick Mahaney December 4, 2011 at 8:34 AM

You are welcome.
I hope to not make any enemies in the process of posting this perspective, but from years of clinical experience I have seen many healthy pure breed dogs that live a good quality of life free from genetic diseases.
Of course, many owners “wreck” their dogs’ health by feeding pet grade foods over many years, not providing sufficient exercise, and not addressing health issues (dental disease, obesity, etc), which happens regardless of breed.
I hope to see you here again!

Patrick Mahaney December 4, 2011 at 10:57 AM

Very good point to bring up the pure breed cat perspective. I do consider non-pure breed cats to be “mutts” as well. The majority of cats I see as patients are DSH (Domestic Short Hair) “mutts”.
Great point about familiarizing oneself with a pure breed dog or cat’s propensity for illness before pursuing a pet. Knowing what you may be getting into from a perspective of health problems can save one’s sanity (and potentially, their financial savings) down the line.
As you point out, any pet, regardless of breed (or mix of breeds) can have illness that may or may not correspond with their underlying genetic.
Thank you for your comments!

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