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Genetic testing and breed-specific health care in veterinary medicine

Aug 17

Categories: Blog

Scientists have found the recipe behind the amazing variety of dog shapes, sizes, breeds and it's a very exciting area for veterinarians in practice. Hundreds of genes interact to produce a physical trait in people and many mammals. For dog traits, apparently the magic number is three genes, that's it!. Analyzing the DNA of 85 dog breeds, scientists found that genetic similarities were grouped into four broad categories. These groupings: wolf-like, herders, hunters, and mastiff-like reveal just how breeders have combined ancestral stock to create new breeds: a few even manage to maintain many wolf-like genes.

Because the field of genetics is expanding and with some new tools, we have learned a tremendous amount about how traits and disease occur and are inherited in dogs. This knowledge is changing how veterinarians approach our patients. The way we use this breed specific knowledge allows the veterinary team to take better care of our patients. By understanding and using these genetic advances veterinarians can provide individual care plans for our patients tailored to meet the needs of the life stage, life style, life expectancy and now individual breed concerns-- even with mixed breed dogs! By identifying breed specific risks and creating a monitoring care plan based on breed background improves our pet parent's relationship with the veterinary team of Animal Health Care and can allow for monitoring, testing, and an even greater increased awareness of breeds at risk allowing for a more rapid diagnosis, breed specific testing and earlier medical, surgical, or dental intervention.

Our pet care team starts from the first time we meet a patient. We take into consideration breed differences when making medical decisions and even picking medications. For instance, it's well known that certain breeds like the Collie or Sheltie have a genetic mutation which makes them sensitive to Ivermectin found in many heartworm preventatives as well as to other very commonly used medications, preventatives, and anesthetic agents.  But not as well known are those who may have these breeds in their mix. So, without testing we may be putting them as a breed at risk and we wouldn't even know.

Much information is published and applied to the 187 recognized breeds and varieties (last count at the 2013 Westminster Dog show) and now this benefit can be extended to mixed breed patients as well. We can use the Widsom Panel Professional Genetic Analysis blood test, a doggie DNA test, to evaluate the pure-bred ancestors within the lineage of the mixed breed dog. The information we get helps to construct an individual health care plan and so that when a patient is diagnosed with a potentially inherited condition and a DNA test is available, we can, once we know the breeds in the mix, use this information to confirm the diagnosis and provide important treatment and prognostic information.

Close to 100% of dog owners talk to their dogs. 81% view their dogs as family members. Many of these family members have gone from the barn yard to the back yard to the back door to the foot of the bed, then into our beds, and now even have better beds than us.  They get many human privileges including, and this is not necessarily endorsed by your pet's vet, but none the less recognized as common, the feeding of leftovers-- sometimes straight from the table, plate, or even fork. Many people would save their pet before they would save a fellow human being. Many also say that they like their pet much better than they like most people. So it isn't a surprise that we want the best health care for them! And, we as the other family doctor can help.

Take my dog Mia.... she came to me a few years ago in need of a home. We had lost our Shiba Inu, Buddy, 2 years before and we were dog deficient. Mia is an easy keeper, not particularly demanding and quite content to keep watch in our yard, hunkering down into the mulch. She only barks when she feels the need to remind us of her preference to be outdoors or if she feels she would like us to join her. She looks like, for all intents, a mix of a Labrador Retriever and a Border collie. So much so that I would have bet on it! But she was a mix breed, Heinz 57, mutt, and her previous owners who had adopted her as her second family had no additional information about her and in fact her veterinary medical record identified her as a Labrador mix. So, I tested her to see what what in this beautiful high gloss black coated dog with a happy raised tail, who seemed to be on guard, protecting her new family by keeping watch in an elegant, quiet monitor mode.

And, here's what I got as a result: Mia is a mix of a Boxer, Chow chow, and an American Foxhound. So now I look at her and I try to see the breeds in my mix breed dog. How could it be that there wasn't even a hint of a Lab or Border Collie? OK, then let's see: see does have a typical jutting jaw bite of the Boxer dog: her bottom jaw is slightly longer than her top jaw. She does have a short Chow chow coat with that northern breed curling tail, but not a speck of the well known purple tongue, and if you subtract the hair coat she does have a hound body shape: taller than most, like the Beagle, and certainly resembling the American Foxhound.

Dogs have to be one of the most diverse species on the planet. How is it that a 2 pound Chihuahua and a 200 pound Irish Wolfhound can have essentially the same DNA code in each? If human were dogs, a pug compared to a Saint Bernard, their height would range from 2 feet to over 30 feet! How is it that many large breed dogs are considerd seniors (ready for their AARF card) at 4-5 years and the smaller breeds are considered seniors only after they reach  10+ years? 

Common characteristics such as loyalty, tenaciousness, or the instinct to herd (not hurt) clearly have a genetic basis. Factors ranging from a dog's nutrition, children in the household, exercise and environmental stimulation can also affect our dogs. It's hard to put it all together but a great place to start is with your pet's veterinarian and the animal health care team. We have many breed books and can discuss pre-purchase or pre-adoption needs of the family in deciding what kind of dog would be best based on questions addressing time, energy, type of yard or not, walking and housetraining areas available (inside vs outside for the smaller dogs), who is in the family, who is going to be involved in training, what kind of grooming ("wash and wear" bath dogs vs haircut requiring) needs, other resident pets and more.

So we really have a good shot at understanding dog behaviors and their disease risks based on their breed and breed mixes. And, there are probably millions of dog owners like me out there willing and eager to help with the field work...

For more information on genetics and genetic and phenotype testing in veterinary practice go to Mixed-Breed Ancestry Analysis at www.WisdomPanelPro.com or Canine Health Information Center (CHICH) at www.caninehealthinfo.org/.