Canine genomic research provides clues to breed development, appearance, behavior and disease
By Kim Campbell Thornton
Andrews McMeel Syndication
Family lore says we have Cherokee and Choctaw ancestry, but genetic testing didn’t bear that out. My dog Gemma, however, can claim to be a New World dog whose genetic ancestry -- at least some of it -- goes back 10,000 or more years to the earliest dogs who migrated with their people to populate the Americas.
Gemma is half-Chihuahua, according to her canine DNA test results from Embark. A study published last month in the journal Cell Reports found that Chihuahuas were among a group of dogs with large amounts of DNA unlike that of other breeds. Those breeds included the American hairless terrier, Chinese crested (not actually from China, despite the name), Peruvian Inca orchid, rat terrier, toy fox terrier and Xoloitzcuintli (also known as the Mexican hairless). Archaeological evidence of an ancient canine subspecies existed, but this study marks the first living evidence of it in modern breeds.
“What we noticed is that there are groups of American dogs that separated somewhat from the European breeds,” says study co-author and dog geneticist Heidi Parker of the National Institutes of Health. “We’ve been looking for some kind of signature of the New World Dog, and these dogs have New World Dogs hidden in their genome.”
Scientists examined gene sequences from 1,346 dogs representing 161 modern breeds to assemble a canine evolutionary tree. It’s the largest and most diverse group of breeds studied to date and includes dogs from North America, Europe, Africa and Asia.
What’s the value of such a study? It has several purposes. For one, the map of dog breeds will likely help researchers identify disease-causing genes in both dogs and humans.
“Using all this data, you can follow the migration of disease alleles and predict where they are likely to pop up next, and that’s just so empowering for our field because a dog is such a great model for many human diseases,” says the study’s senior co-author and dog geneticist Elaine Ostrander of the NIH. “Every time there’s a disease gene found in dogs, it turns out to be important in people, too.”
One interesting finding was evidence of shared diseases across groups of dogs. For instance, collie eye anomaly (CEA) is a disease that affects development of the choroid in herding breeds such as the Australian shepherd, border collie, collie and Shetland sheepdog. But it also affects Nova Scotia duck tolling retrievers, which until this study were not known to share ancestry with herding breeds. The analysis showed that collies and Shetland sheepdogs were strong but undocumented contributors to the duck tollers' ancestry, making them the likely source of the CEA mutation in that breed.
The study also highlighted how the most ancient dog breeds evolved to perform certain roles. Humans likely began with certain types of dogs -- such as sleek, leggy dogs with strong prey drives for hunting and mid-size dogs for moving flocks -- and then further selected for specific physical traits. The cultural move from hunting to agriculture may have instigated the formation of breeds in multiple regions.
“I think that understanding that types go back a lot longer than breeds or just physical appearances do is something to really think about,” Parker says.
More than half the dog breeds in existence have yet to be sequenced. The researchers plan to keep collecting dog genomes -- often acquired from DNA samples provided by owners at dog shows -- to fill in the gaps.
Gemma? She’s lording it over our cavalier King Charles spaniels because her ancestry goes back farther than theirs.
Q: My 4-month-old Rhodesian Ridgeback puppy ate my sofa. Literally! What can I do? I can’t afford to buy much more new furniture. -- via Facebook
A: Congratulations -- you have a normal puppy! That’s the good news. The bad news is that without plenty of training and supervision, things can get worse before they get better. Puppies are hard-wired to explore their environment, and since their paws don’t have opposable thumbs, they use the next best thing: their sharp teeth.
But you don’t have to lose any more furniture. Chewing and scratching provide pets with exercise and mental stimulation, but they don’t have to be destructive -- at least not to anything other than their approved toys. Puppy kindergarten followed by advanced training, as well as plenty of interactive exercise and playtime, can help you teach your pup how to channel his chewing -- and his energy, in general -- into more productive and acceptable activities. Here are some tips.
-- Put his brain to work with puzzle toys that make him think. Some favorites are the Snuffle Mat and the Nina Ottosson Twister. Believe it or not, a good mental workout can leave him too tired to even think about eating your furniture.
-- Provide interesting and long-lasting chew toys. I like the Kong not only for durability but also for its “stuffability.” Load it up with peanut butter, baby carrots, kibble and other tasty treats, freeze it, and then let him go to work trying to get all the goodies out.
-- When you see your puppy chewing on something he shouldn’t, get his attention so he turns away from it, and then give him an acceptable chew toy. Praise him when you see him chewing on his toys; it’s important for him to learn what’s OK for him to chew as well as what he shouldn’t. -- Mikkel Becker
Do you have a pet question? Send it to firstname.lastname@example.org or visit Facebook.com/DrMartyBecker.
-- A new generation is in love with pets. Members of Generation Y, or millennials, have surpassed the baby boomers by 3 percentage points to account for 35 percent of all pet owners, according to the latest National Pet Owners Survey from American Pet Products Association. They make up more than half of reptile, small-animal and saltwater fish owners. In other survey results, the number of pet-owning households is up, from 79.7 million in 2015 to the current 84.6 million. That means 68 percent of American households now include a pet. Spending on pets, including veterinary care, increased to $66.75 billion.
-- Record-breaking animals? Guinness World Records has them. They keep tabs on everything from longest tail to loudest purr. Among the record holders are Merlin, a 13-year-old tuxedo cat whose purr registers 67.8 decibels -- as noisy as an air conditioner. Irish wolfhound Keon lays claim to the title “longest tail.” His measures just over 30 inches. Didga the cat can perform 24 tricks in the space of a minute, and Purin, a 9-year-old beagle, caught 14 balls with her paws in a minute’s time. And a blue-and-gold macaw named Skipper Blue can place 19 rings on a target in one minute.
-- Find out which pet parasites and diseases are of concern in your area at petsandparasites.org, the consumer page for the Companion Animal Parasite Council. It has maps for tick-borne diseases such as Lyme and ehrlichia; internal parasites, including hookworms and roundworms; giardia, a protozoan parasite that can affect dogs and humans; plus infectious diseases such as feline leukemia virus and feline immunodeficiency virus. Choose your state or county to find the percentage of positive cases. Parasite forecasting predicts a big year for heartworms and Lyme disease. The organization also plans to begin forecasting other diseases and parasites. -- Dr. Marty Becker, Kim Campbell Thornton and Mikkel Becker
ABOUT PET CONNECTION
Pet Connection is produced by a team of pet-care experts headed by "The Dr. Oz Show" veterinarian Dr. Marty Becker and award-winning journalist Kim Campbell Thornton. They are affiliated with Vetstreet.com and are the authors of many best-selling pet-care books. Joining them is dog trainer and behavior consultant Mikkel Becker. Dr. Becker can be found at Facebook.com/DrMartyBecker or on Twitter at DrMartyBecker. Kim Campbell Thornton is at Facebook.com/KimCampbellThornton and on Twitter at kkcthornton. Mikkel Becker is at Facebook.com/MikkelBecker and on Twitter at MikkelBecker.