Unlocking the genetic secrets of your dog
Want to know what mix of breeds your dog is? Want to know which hereditary disorders your mixed-breed or purebred dog is at risk for or carries?
About a decade ago, companies began marketing panel tests that incorporated multiple genetic markers to help dog owners, breeders, and veterinarians determine a dog’s ancestry. Recently, companies have expanded into panel testing for multiple genetic disorders in dogs.
Among the companies offering both breed identification and testing for genetic disorders are Mars Veterinary, which offers the Wisdom Panel, and the startup Embark Veterinary Inc., which operates in partnership with Cornell University College of Veterinary Medicine.
In a related development, the AVMA House of Delegates passed a policy in January on “Inherited Disorders in Responsible Breeding of Companion Animals.” The policy encourages research, continuing education, and outreach on inherited disorders in companion animals (see JAVMA, March 1, 2017).
Tests for breed identification can provide information about the genetic makeup of a dog and, potentially, its predisposition to certain conformational, health, and behavioral characteristics, said Dr. Urs Giger, a veterinarian with a focus on clinical genetics as a professor at the University of Pennsylvania School of Veterinary Medicine. Regarding panel testing for genetic disorders, he said, “This is really a breakthrough and will be something that will be changing the approach to hereditary disease screening.”
Testing to determine the ancestry of mixed-breed dogs is more of a novelty in the mind of Dr. Jerold Bell, a solo practitioner at Freshwater Veterinary Hospital in Enfield, Connecticut, and adjunct professor of clinical genetics at Cummings School of Veterinary Medicine at Tufts University. But he believes that panel testing for genetic disorders could become mainstream in a short period of time.
Mars Veterinary, a business unit of Mars Petcare, introduced the Wisdom Panel to veterinarians in 2007 as a blood test and to consumers in 2009 as a cheek swab test. The first versions of the panel focused only on breed ancestry, using 321 genetic markers to identify the breed makeup of dogs.
Dr. Angela Hughes, a veterinarian who is the veterinary genetics research manager for Mars Veterinary, said blood is the gold standard for a good-quality DNA sample, and the best use of the test results is in conjunction with a veterinarian. She said, “It’s one thing to know that your dog is a German Shepherd–Chow mix. It’s another to understand what that means medically and behaviorally and nutritionally for the dog. It takes it from a gee-whiz curiosity level to an applicable test.”
Dr. Hughes said Mars Veterinary has built a large database of purebred dogs and improved the Wisdom Panel algorithm over time. By 2014, the panel also had expanded to include testing for 13 mutations and markers associated with genetic disorders.
In 2015, the company switched to a panel with 3,000 genetic markers, incorporating the MyDogDNA test from Genoscoper Laboratories of Finland.
At $84.99, Wisdom Panel 4.0 is a cheek swab test for breed identification that also screens for the mutations associated with multidrug sensitivity and exercise-induced collapse. Blood tests that provide breed identification and screening for more than 140 mutations and markers associated with various disorders, including multidrug sensitivity and EIC, are available through Banfield Pet Hospital, a Mars Petcare subsidiary, and through veterinarians who offer a test from Royal Canin, another Mars Petcare subsidiary.
For dog breeders, the $99.99 Optimal Selection cheek swab test provides an analysis of dogs being considered for breeding that covers genetic diversity of the individual dog, the diversity of the dog in relation to others in the breed, and the overall diversity in the breed; tests for traits such as coat colors and types; and screening for more than 150 mutations and markers associated with disorders.
Mars Veterinary incorporated the mutations for multidrug sensitivity and EIC into its Wisdom Panel 4.0 “because we felt those were ones that owners could actively work to improve the health of their own dog by avoiding situations or scenarios where the dog could get into trouble,” Dr. Hughes said.
She said many dog owners wonder what mix of breeds their dog is. She had her own dog for nine years before testing. According to the results, he is not a Papillon but a Cocker Spaniel and Maltese mix.
Regarding panel testing for genetic disorders, Dr. Hughes said, “We feel it’s going to, in the next five years or so, really transform the veterinary practice. If you know in advance, when this dog is a puppy, how it’s going to deal with certain medications, what is its risk for a number of diseases, that sort of thing, it’s really important to incorporate that.”
For cat breeders, Mars Veterinary launched a $69.99 Optimal Selection cheek swab test in November 2016. The test screens for 29 mutations and markers associated with various disorders and provides an analysis of traits such as coat color and length.
Embark Veterinary Inc.
Embark Veterinary Inc., in partnership with the Cornell University College of Veterinary Medicine, introduced the Embark Dog DNA Test last year. The $199 cheek swab test analyzes a dog’s ancestry, risk of genetic disorders, and heritable traits.
The company was founded by Ryan Boyko and his brother, Adam Boyko, PhD, chief scientific officer and an assistant professor of biomedical sciences at the Cornell veterinary college. The brothers had been traveling the globe collecting DNA samples from dogs as part of their passion for canine genomics.
Dr. Boyko said they founded Embark to deploy a model “of having people who wanted to know more about the genetics of their dog actually mailing the DNA to us, and we could tell them about that, instead of us having to go out all over world to do it.”
The Embark test incorporates more than 200,000 markers, he said, “and, now, that dog can get enrolled in all sorts of genetic association studies.” He conducted a genetic association study in his laboratory with 5,000 dogs, but human studies can have tens or hundreds of thousands of subjects.
The current version of the Embark test reports results on more than 160 mutations and markers associated with disorders as well as ancestry and traits such as body size. Dr. Boyko said, “We want (Embark) to be a tool that veterinarians can use.” Embark has created a downloadable report for veterinarians to see the key genetic data for a dog at a glance. The company offers its test to veterinarians at wholesale price to sell in their clinics.
With genetic testing in dogs, Dr. Boyko said, most dog owners think first about breed mix, but then think about health. He said breeders are interested in testing for genetic disorders and genetic diversity.
Embark will send updates to customers if researchers find a new genetic mutation or marker that is associated with a disorder and that is testable on the company’s platform. The company also is validating tests for additional genetic disorders.
Dr. Boyko said Embark can’t diagnose a condition in a dog. He said, “All we can do is give information that will be useful for a veterinarian to know in order to make the diagnosis. Our goal is to cut out unnecessary testing and to reduce the amount of time it takes a vet to make a successful diagnosis,” by providing one panel test for multiple disorders.
In October 2016, Embark partnered with Dognition, which sells online assessments of dog cognition, to study dog genetics and behavior. Dr. Boyko and other researchers will explore the origin of behavioral tendencies, effective training methods for various ages and stages, the effects of environment and breed on behavior, and the rate of cognitive decline in relation to genetics and breed.
Dr. Giger of the University of Pennsylvania says genetic evaluation for dog breed and appearance is of general interest and can be helpful in, say, predicting the adult size and characteristics of a mixed-breed puppy. He said, “Some of it is also just keen interest in knowing more about ancestry, as it is in humans.”
He said screening dogs for genetic disorders can guide diagnosis, treatment, and breeding. A dilemma is deciding whether it is valuable to screen a dog for all known genetic disorders or to restrict screening to disorders recognized in the dog’s particular breed.
“There are certain breeds where specific mutations recognized in other breeds have not been reported before, and we do not yet know for that particular breed whether that (mutation) is going to cause the same disease, a more severe disease, or no disease,” Dr. Giger said. “That’s probably particularly important for genetic markers and predispositions to disease rather than established specific disease-causing mutations.”
Dr. Giger said dog owners need genetic counseling alongside panel testing. He said, “It will be very daunting for a primary care clinician to analyze the huge amount of information and guide owners and breeders about each abnormal test result and associated disease.” He said there is a need for written resources, contacts for more information about the meaning of test results, and, in some cases, involvement of veterinary genetic counselors.
Dr. Giger was an author of a study led by researchers from Genoscoper Laboratories and the University of Helsinki involving the MyDogDNA panel test (see story). He believes panel testing, not testing for individual markers or mutations, is likely to be the way of the future. He said panel testing will make the whole process a lot less expensive and much more streamlined. Panel testing also will result in better estimates of the breed-specific prevalences of certain mutations or markers and can be a research tool to generate new information.
An important issue still to be resolved is that some genetic mutations that have been discovered have been patented, limiting the availability of testing. In 2013, however, the Supreme Court held that naturally occurring DNA sequences cannot be patented.
“We are in the best time to eliminate many of these known devastating diseases and genetic predispositions, and a lot more tests, and possibly whole genome sequencing, will become common practice,” Dr. Giger said.
At Freshwater Veterinary Hospital, Dr. Bell does not use panel testing for genetic disorders in dogs yet. He said, “Ideally, it’s going to develop where we will have all of the known genetic markers in these panels, so that you run it on one patient, and then you know exactly what mutations they carry.”
Right now, he said, one breed has this test, and another breed has that test. One test is run at one place and one at another. For some breeds, you have to run multiple tests at different places. Dr. Bell said, “You’re paying for each individual test and drawing multiple either blood samples or cheek swabs to send to all the different places. It makes it very confusing, and it makes it very arduous to just try to do the right thing to determine what the genetic background is of a particular dog.”
With panel testing, he said, the question of whether to test disappears, and the question is what to do with the test results. He said, “To me, that’s a great first step.”
But is it the burden of the testing agency or the responsibility of veterinarians to interpret results and provide genetic counseling? Dr. Bell said some breeders might understand the results better than some veterinarians.
“There’s a whole lot of education that is going to need to get filled in, in terms of using these the right way, because there is a great chance of using these tests the wrong way” and actually limiting genetic diversity, he said.
Dr. Bell also expressed concerns about minimum standards for laboratories that offer genetic testing.
With panel testing, he believes it’s best for dog owners to work with veterinarians and for veterinarians to learn more, through avenues such as continuing education, about what the tests mean and how to provide genetic counseling.
At AVMA Convention 2017 this July in Indianapolis, Dr. Kari Ekenstedt will present sessions on genetic testing in dogs and cats, common canine and feline genetic disorders, determining the breeds in a mixed-breed dog, and genetics in purebreds, designer breeds, and mixed breeds.
Dr. Bell has had clients who did a breed analysis of their mixed-breed dogs for curiosity’s sake, but not for medical reasons. He believes that companies offering panel testing for genetic disorders alongside breed analyses could make a difference in disease prevention.
Regarding panel testing generally, he added, “The bottom line is I think that this is the future of genomic medicine.”
Group launches initiative to harmonize genetic testing for dogs
The International Partnership for Dogs has launched the Harmonization of Genetic Testing for Dogs initiative to provide practical support to address challenges accompanying the increasing emergence of new canine DNA tests and testing laboratories.
According to an announcement, “With no existing national or international standards of accreditation, or standardization oversight group, there is a growing need for a reliable third party neutral organization that can provide guidance surrounding test reliability, laboratory quality assurance processes and procedures, test applicability by breed, and provide counseling regarding interpretation and best use of genetic test results.”
The goal of the IPFD initiative is to create an open-access, searchable, and sustainable online resource to do the following:
- Catalog information provided voluntarily by commercial test providers for genetic testing in dogs.
- Describe expertise, quality assurance, activities, and resources of the test providers.
- Host expert panel reviews of genetic tests and the tests’ reliability and applicability.
- Coordinate a program for standardized proficiency testing, potentially with peer review and auditing.
- Assemble existing and new resources for genetic counseling and education, plus provide the foundation for future developments.
The first phase is to develop a working prototype of the online resource. A multiple-stakeholder steering committee will oversee the initiative. Initial funding for the prototype comes from IPFD Founding Partners, the Orthopedic Foundation for Animals, and the American Kennel Club Canine Health Foundation.
Related JAVMA content:
Disease-associated gene variants widespread across dog breeds (March 15, 2017)
AVMA passes policy on responsible pet breeding (March 1, 2017)