Friday, December 19, 2008

And now for something completely different.

Today I'm going to do something a little backward on MoT. In fact, let's talk about the merits of mixed breeding by design.

Wait wait, don't stone me!

I want to talk about outcrossing. This is something I touched on briefly in this post, but I've started looking into it a bit more since...

We know there's a problem in the dog world (and if you'd rather think there isn't, move on because this blog ain't for you). Purebreeds are becoming increasingly defective and thanks to closed registries we're whittling the gene pools down to puddles. What's to be done? How can we fix this mess we've created? Two solutions should be staring us in the face - the third remains a little hazy. I'm talking, of course, about:
A) Changing the AKC breed standards
B) Switching from closed to open registries
C) ...And outcrossing.

To start with, let's cover the history of the bobtail boxer. International Kennel Clubs recognize more than fifty breeds currently, the boxer included, with docked tails. Tails are docked for reasons of hygiene (hair matting under the rump), or for practical reasons, mainly in gundogs (whose tails can become tangled, torn and injured in the field) and working terriers (who have to maneuver in tight spaces). And, of course, we dock to meet breed standards. There are plenty of people on both sides of the docking fence, but recently breeders have been under more pressure to stop docking and cropping. There are people who'd rather be left alone to dock their dogs, people who recognize that only trained and competent professional should dock puppies, and people who think it should be banned altogether.

In the face of such a ban, one boxer breeder decided not to sit at home and complain, but to do something about it. There are a handful of breeds with a natural bobtail gene: these include Boston terriers, Pembroke Welsh corgies, Polish Lowlands, English bulldogs and Australian Shepherds. Dr Bruce Cattanach, breeder and geneticist by profession, took one of his boxer bitches and crossed her with a Pembroke corgi. This was the result:

Dr Cattanach then began backbreeding with typey purebred boxers. By the fifth generation, he had produced this:

This article can tell you about the whole process and give a play-by-play of each generation. Ultimately, Dr Cattanach introduced the natural bobtail gene and managed to breed back to "show quality" boxers. Ta-da! Somebody smart and qualified saw something going on with his breed, and had the perseverence to change the situation. More bobtails. Not only are these boxers being spread across Europe and Australia, they're recognized by the UKC.

There are other backcross projects going on. Breeders have been trying for several decades to eliminate uric acid defect in Dalmatians, a breed riddled with genetic defects. Dalmatians have suffered from uric-acid stones for over a century now; no other breeds are affected. High levels of uric acid can result in bladder stones - this is an emergency. These stones often need to be removed surgically, and high uric acid hits up just about every Dalmatian.

In the 70s, Dr Robert Schaible, a geneticist and breeder (not unlike Dr Cattamach), bred a Dalmatian bitch to a champion pointer dog in order to introduce normal levels of uric acid back into Dalmatians. The resulting pups, though they didn't look a whole lot like Dalmatians, all excreted normal uric acid levels. Dr Schaible started backcrossing, selecting one pup from each resulting litter for Dalmatian traits and low UA levels. Only the one pointer has been used, but the AKC refuses to register the backcrossed dogs in spite of the project receiving support from the Dalmation Club of Northern California (home to the Backcross Project). This project quietly persists, producing more and more Dalmatians with normal UA levels; the AKC continues to ignore it. In September 2008 the very question of discussing registry for these dogs was shot down by the parent club.

Seventh-generation backcross.

I can't help but wonder why it is the backcross developed for largely aesthetic purposes is embraced so much more widely than the backcross designed to cut back on health issues...

Should more backcrossing projects be encouraged and nurtured? Is this really an alternative, in the hands of gene-savvy, qualified breeders? Are these problems ones that could be eradicated by changing the breeding policies of purebred dogs?

Until somebody changes my opinion, I'd like to see more careful, controlled, supervised-by-scientists out- and back-crossing projects for our "emergency" breeds. The pug may be too far gone to save itself; maybe beagle genes really are the answer. Maybe the Shar-Pei needs a serious face-lift in the form of a non-wrinkled mate. Maybe this is the only hope of the Neapolitan mastiff. Who knows?

It can't hurt our breeds more than we already have.


Linny said...

I completely agree with you about outcrossing to produce healthier dogs. The work that's being done with Dalmatians and some other breeds is admirable.

However, “bobtail boxers” are a whole different ballgame. They weren't aiming to produce a healthier dog: just a dog with a shorter tail. Unfortunately, to do that they had to introduce even more health problems.

The gene that was introduced from Pembroke corgis for a bobtail is dominant. That means that dogs only need a single bobtail gene (let's call it B) along with a normal longtail gene (let's call it b) to have a bobtail. So longtail boxers will be bb, and bobtails will be Bb. So far so good.

However, the bobtail gene also brings along with it the so-called "lethal gene". If you cross two bobtail boxers (ie Bb with Bb), those pups who pick up two copies of the bobtail gene (ie those that are BB) never develop properly. They die, either early, during embryonic development, or later, in foetal stages. The puppies are usually reabsorbed in the uterus before they come to term, and are never born alive, but is that really something that's desirable?

And if that wasn't enough, there's another problem. The gene pool of bobtail boxers is very, very tiny. All of these dogs (every one) is a recent descendant of the single Pembroke Corgi who was used to introduce the bobtail gene in the first place, back in 1991. This means that if two dogs from bobtail lines are bred together, the chance of a deleterious recessive gene emerging is very high indeed. And the more times you do it, the greater the risk becomes.

Even the originator himself (Cattanach) said dogs from bobtails lines should not be bred with each other, because of the dangers inherent in introducing recessive problems. In his own words, "we have everything to lose and nothing to gain” by crossing them. And that goes for ALL the dogs from bobtail lines, regardless of whether or not the dog itself is bb (ie longtailed) or Bb (bobtailed). How does anyone realistically propose to police this restriction, now that the bobtail gene has been released into the general boxer population?

I think boxers already have enough to deal with (aortic stenosis, cardiomyopathy, tumors, lymphoma etc). Why risk introducing even more health problems into the breed, just for the sake of a shorter tail?

I believe the time, effort and resources that have been put in to creating the “bobtail boxer” would have been far better expended trying to eliminate the health problems that already exist in the breed.

muttpuppiesontrial said...

You're right. Bobtail boxers are a good example of outcrossing, since Dr Cattanach knew what he was doing, kept the UKC informed, and ultimately produced exactly what he'd envisioned. Can you imagine if that kind of drive were applied to eliminating health problems? Breeding for aesthetics is exactly what got us into this mess in the first place.

That limited gene pool is also, I think, the flaw of the Dalmatian Backross Project. 50% of each backcrossed litter has normal uric acid levels, which is a huge step. Why not start again with another Dalmatian/pointer outcross? Unfortunately they have no plans to do so, and now that the AKC is refusing to even acknowledge the dogs, it doesn't look like they'll get the support to expand.

GoLightly said...

Excellent Post.
Exactly what purebred dogs need, an infusion of health.

water_bearer said...

Linny has made a far more informed argument than I would, although I tend to agree with most of it. In theory, outcrossing is a good idea except there are so many variables to take into account that it renders a) the likelihood of it actually occuring in the first place and b) executed successfully at that, increasingly unlikely.
I believe that there are certain all purpose or strictly companion dogs that could be crossed with similar looking and behaving breeds or mixes, which were also not too close on the family tree, and it would ultimately only help alleviate major health issues that could otherwise not be eliminated through careful purebred breeding because some breeds have gotten themselves so painted into a corner of the gene pool they have few other choices. However, while I'd hate to think of myself as too breedist, I know I am sometimes and rightfully so in some cases I think. There are some breeds whose popularity or long history has given them the golden ticket of having a large and diverse gene pool all over the world and therefore even less of an excuse for the myriad health issues they face. Case in point: the German Shepherd. Toplines should be neither on a 45 degree friggin angle that ends in spindly crooked hind legs, nor are Shepherds ever supposed to be described as "big-boned" or have roach backs. Instead of fighting over which deformity is the most cool, the various factions should shut the hell up, get on the same page, and start formulating a plan that everyone can get behind to return this dog to its original form and function. All the pieces are there but it requires everyone to agree first off, and for people to seek out breeders with unrelated lines, perhaps even from the other side of the pond, and not because they are in one "back" camp or another. Hip dysplasia, temperaments, thyroid problems... all of it can be taken care of together and just with knowledgeable breeders. The difficulty factor is amped up only by people's egoes getting in the way.
With breeds that are less numerous but have one really bad problem, like the messed up faces on Japanese Chins, that's an easy fix in a couple of generations. More popular ones like Pugs or Bulldogs may have no other choice but to outcross and much like the Dalmation, within a few generations you wouldn't be able to tell the difference, except for the fact that the dog wasn't deformed in the snout and could actually breath.

The rest I'm afraid may have to be fixed by only the most qualified experts. Again though, aren't they really just like any other breeder? Their dogs may look the same and have the same coat texture and you may have gotten rid of the health problems, but then there's the hardest factor of all to see in puppies, and that's personality. What if those Dals turned out to be agressive non-family dogs with high-prey drive? You have to be careful.
Neopolitan Mastiffs are just f*cked.

water_bearer said...

Oh... and are you following Puppygate?
Let's hope our soon-to-be VP does a better job vetting his staff and any foreign dignitaries he's to meet, than he did the puppy mill he got his 6-week old puppy from.

water_bearer said...

I tried to leave a "Merry Christmas" message yesterday but for some reason it didn't go through. Anyway... hope everyone had a nice holiday, oh and happy Boxing Day.
I saw this on our local news today, and I thought I'd send you the transcript. See if you can figure out why. Gotta love our governor. What a douchebag.