Dogs and the Myth of Hybrid Vigor

I'd like to tackle a common myth that anti-breeder zealots throw around to try and convince people mutts are better than purebreds: the notion that a mutt or crossbred dog has "hybrid vigor."

Hybrid vigor is a real thing, though. But like Inigo Montoya of Princess Bride, they keep using that phrase and it doesn't mean what they think it means.

Hybrid vigor, according to most reputable sources, is the tendency of a hybrid animal to suffer none of the common ailments of either parent species. This is why mules are renowned for having better health than your average horse OR donkey--the blend of the two different species (generally a donkey jack and a horse mare) produces an animal of superior utility. George Washington was a huge supporter of the donkey breed known as Mammoth Jacks, because when the jacks were put to horse mares, they produced the BEST mules.

THAT is goddamn hybrid vigor. Likewise, ligers (tiger-lion hybrids) tend to be HUGE, powerful, and scary compared to their parents.

However, anti-breeder/anti-purebred people tend to forget one key element: different breeds of dog are not considered different species. Think back to the mule, okay? Horse + horse = horse; donkey + donkey = donkey; donkey + horse = MULE.

In case you need it spelled the hell out, DOG + DOG = DOG. Same species. No hybrid vigor.

I get what they are trying to say, though. They are mistaking the term "hybrid vigor" for "heterosis," which simply means that some crossbred animals are superior in some way (health, utility, et cetera) than purebreds. And yes, it happens. I'm a huge fan of, say, grade horses crossed for a reason.  Not the morons who put their shitty-conformed AQHA reject mare to an Andalusian in hopes of selling the "part Andalusian" foal for big bucks, but people who cross horses for a REAL PURPOSE.

Take, for example, the National Show Horse. It's now recognized as a breed unto itself. Back in 1981, people wanted the size and awesomeness of the Saddlebred, as well as some of the gaits (Saddlebreds can be three, four, or five gaited), and the flashy prettiness of the Arabian. After some crossing, they came up with a consistent (and consistently beautiful) horse with size and substance but grace and finesse. Now that is crossbreeding with heterosis in mind!!!!

So how does that translate into dogs? Well, if you have a real dandy of a Cattle Dog bitch, and want a superior herding dog but cannot locate another good Cattle Dog, you could do worse than an awesome herding-proven Border Collie or Aussie. I know someone who has blended Australian Shepherds, Cattle Dogs, and Border Collies into their own little slice of awesomeness. Her dogs are excellent for herding and farm guarding; many of her pups are used on livestock and their owners have found them to be ideal.

You can even reach a state of heterosis within a breed, if you try hard enough. Years ago, the gene pool for purebred Basenjis in the United States was pretty small. Breeders, concerned about the fate of their breed, went on a mission to Africa (where the dogs still live with indigenous peoples the way they have for countless generations) and selected a number of dogs to bring back, thus infusing the Basenji breed with much needed genetic diversity. Acquiring those new genes counts as heterosis.

So! What does this have to do with rescue/shelter mutts? SIMPLE. The zealots would have you believe that every crossbred mongrel has superior health/genetics than the parents.

While it CAN be true, it usually ISN'T. Let me explain with a hypothetical (but sadly common) story:

John Q. Asshole buys a shitty Labrador bitch puppy from some dude on Craigslist. Her breeder didn't hip or elbow test her, and she has hip dysplasia. Her owner, who is a shitty owner, lets her run loose all the time. He's also a stingy bastard and won't pay to get her spayed. The combination of having a uterus AND being allowed to run willy nilly all over the place means that eventually, some dog knocks her up. For this example, let's say it's the intact male German Shepherd a few blocks away. He is a shitty Craigslist acquisition too, and he also has hip dysplasia.

John Q. Asshole comes home one day to find a bunch of funky-looking newborn pups on his living room floor. After dealing with puppy shenanigans for a while, he dumps the whole litter at the local shelter.

Rescuers assure well-meaning, kind-hearted potential adopters that, because they are mixed-breed puppies, they have HYBRID VIGOR!!! Oh yes, they won't suffer ANY of the health problems that plague ALL PUREBRED DOGS. Sadly, they have probably bought the lie hook, line, and sinker, and so they are VERY convincing.

Jane Niceperson, wanting a pet and hoping to save a shelter dog, listens to the shelter people and decides to adopt one of the puppies.

A year later, her rambunctious puppy has to undergo invasive surgery to correct the hideously genetically deformed hips inherited from the shitty dogs who happened to pass that little doozy on.

See, here's the thing: most shelter mutts are crossbreds of common breeds, and the people who tend to be irresponsible enough to let their dogs indiscriminately breed tend to also be unlikely to buy their dogs from good/reputable breeders who test for common defects, and many breeds share similar common defects. This is why I hate it when people who own Doodles claim their dogs have superior genetics (more on Doodles in a future blog post).

Now, let's look at another hypothetical scenario:

John B. Goodbreeder has been involved in Earthdog trials for years. He loves his purebred West Highland Whites, and while his focus is on their utility as earthdogs, he also tries very hard to ensure his dogs conform to the breed standard conformationally. His favorite bitch is the best dog he's ever owned, and he feels she is ready to pass on her superior work ethic, conformation, and instincts. First, he has her tested for all possible genetic defects--after all, if she could pass on a terrible defect, she shouldn't be bred! To his relief, she comes back clean as a whistle. Next, he begins looking at potential sires. Several are turned down because they aren't health tested. Another for not having a good enough record. Finally, he finds the right sire: the dog has been titled in both conformation showing AND Earthdog Trials, as well as being health tested and clear of defects!

The (supervised) breeding takes place, while John B. Goodbreeder begins screening people who have displayed interest in reserving a puppy. The puppies are born. They are amazing!!!

Joan Niceperson, Jane's sister, has had three Westies. Recently, her beloved old Westie died of old age. She misses having a dog, and dearly loves the wonderful West Highland White breed. Her friend (who attends Earthdog trials with a pair of Jack Russels) tells her about John's litter. Joan calls him and after discussing her needs in a dog and such, he puts her down for a reserved puppy.

Puppies get born, raised, and (when old enough) sent home to their new owners. Joan is thrilled with her new pet!!! And her little Westie puppy is totally free of inheritable health problems, as well as guaranteed healthy via a contract with the breeder.

So! Which dog would YOU claim has "superior genetics?!" The shitty-hipped mutt who will endure pain and arthritis all it's miserable life (while also costing a veritable fortune to it's owner) thanks to inherited defects? Or the puppy carefully planned and bred from sound, health-screened parents?

Are there cases of crossbreds having better genetics than their parents? Sure! Are they the vast minority of crossbreedings? YES! Are there purebreds with inherited problems? Of course!!! Can that be avoided by purchasing puppies from breeders who health-test the parents before breeding? FUCK YES.

Here's my personal anecdote: I have never had a dysplastic purebred. In all the dogs I've owned, not ONE purebred has had shitty hips. Most were German Wirehairs from Jagersbo Kennel (they no longer breed GWPs though, sadly) and they were sound, healthy, perfect. However, I've also had a purebred German Wirehair, a purebred Golden Retriever, and a purebred Cocker Spaniel. All with awesome hips (though the Cocker had a crappy conformed back end, aesthetically; c'est la vie when getting a pet-quality dog!) and no genetic problems or defects.

I also own a little rescue dog. She's a little mutt; she's a cross between Chihuahua and Dachshund. She has bilateral luxating patellas as well as a form of hip dysplasia. Among a litany of other health problems and defects.

SO MUCH FOR HYBRID VIGOR, eh?

This blog entry was originally posted on Jan 22, 2014 @ 20:35. It has been re-posted here for posterity