Outcrossing: What is the ISSA Trying to Accomplish?

We really want to emphasize that we are NOT trying to change the breed. We love Shilohs--and because we love them, we want to pursue strategies to keep our beloved dogs healthy far into the future. Sustainable breeding of healthy, stable, beautiful dogs is the holy grail we are after.

Which leads us to the question: if we want Shilohs to stay Shilohs, won't introducing a totally different breed of dog into the gene pool really mess things up?

The answer is: not really, and not for long!

Few Genes Influence Appearance

The first thing to realize is that only a very small percentage of the genes in a dog have anything to do with its appearance. For example, a team of investigators co-led by researchers at Stanford University School of Medicine, Cornell University and the National Human Genome Research Institute has found that the genes that differentiate size and build in all breeds, from the smallest Chihuahua to the largest Irish Wolfhound, are determined by only a few genetic regions.

"We've found that only six or seven locations in the dog genome are necessary to explain about 80 percent of the differences in height and weight among dog breeds," said Carlos Bustamante, PhD, professor of genetics at Stanford. "In humans these are controlled by hundreds if not thousands of variants." You can read the whole story here.

Likewise, the genes controlling things like color, coat type, muzzle length and ears are relatively few when considered next to the entirety of the 19,000 genes in a dog. Because the number of genes controlling appearance is so small, and the trait inheritance relatively simple, it takes almost no time at all to return to the appearance of the original breed after outcrossing. But you don't have to take our word for it! Below, check out two dramatic examples of outcrossing to different breeds, and see how quickly the dogs returned to the original breed's type.

The Stockard Experiment

In the early 1900's a clever scientist named Charles R. Stockard set out to determine the inheritance of a number of physical traits in dogs. Back in those days, there wasn't any study of genetics; instead you studied inheritance. If you wanted to figure out how traits in animals were inherited, the best way to do so was to breed them, and document the process. Happily, Stockard did!

Below is one of the published plates from his study. In this experiment, he crossed a German Shepherd with a Bulldog--a Bulldog!--to see how the trait of skull type was inherited.

It is fascinating to see how the first-generation pup from that match (pictured in the center) doesn't look like either parent, but instead something related to a mastiff breed. In the second generation breeding back to German Shepherds, the pups are seen (at the bottom) to already look like shepherds again, albeit with faded color and slightly soft ears. If a third generation cross to German Shepherds had been done with those pups, it's easy to see that the progeny would again look like German Shepherds--even being 12.5% Bulldog.

Stockard's book, The Genetic and Endocrinic Basis for Differences in Form and Behavior, was published posthumously in 1941, and is available publicly online. You can search it out, or take a look at this collection of images from the work here on the Institute of Canine Biology web site.

Dr. Cattanach's Boxer-Corgi Cross: the Bobtailed Boxers

What about evidence from more modern days? In the 1990's, when controversy was building over whether the docking of tails in dogs was ethical, one Boxer breeder decided to take a try at breeding a Boxer with a naturally bobbed tail. His name was Dr. Bruce Cattanach and the dog he choose to cross into boxers? The Pembroke Welsh Corgi. Believe it or not, by the second generation he produced a female that looked almost completely Boxer. When she was mated to a purebred Boxer male, the third generation dogs were recognizably Boxers. By the 4th generation the line was registered by the UKC as Boxers, and winning in the show ring--even being 6.3% Corgi!

The short version of the story of his bobtailed Boxer project can be read here, on the website of the American Boxer Club. Click on the links in the text to see the F1 dog, and compare to Jane the F2 dog (who already looks like a white Boxer). Then notice how the next generations looked just like full Boxers! If you have a little time, you might peruse the doctor's actual articles written during the course of the project, with lots of photos, to be found on his genetics and articles page here.

Other Outcrossing Projects Today

We aren't the only ones persuing outcrosses to different breeds to gain more genetic health and longevity. The Norwegian Lundehunde was in dire danger of extinction, so it is currently undergoing an outcrossing project. The Dutch Wetterhoun (water dog) has chosen recently to start an aggressive outcrossing project utilizing more than four different breeds, including the Standard Poodle and the Labrador Retriever (though it's in Dutch, you can find their site here). Both of these projects are guided by population geneticists with the full cooperation of the breeders.

The Institute of Canine Biology has a page with links to these outcrossing projects, and also to the Irish Red and White Setter outcross project. In addition, the Saarloos Wolfdog breed in the Netherlands has begun its own crossbreeding project for added diversity. Here in the USA, a dedicated group of Bernese Mountain Dog breeders and fanciers has decided to attempt to improve the health of their dogs by beginning an outcrossing project.

We hope that reading all this and looking at the pictures hasn't just educated you--we hope it has excited you! There is so much potential for a healthier future for purebred dogs through the utilization of crossbreeding programs like these. We're proud to be taking this step for our breed--NOT when we have an emergency situation, but now, when we can be proactive. Preventing ill health in the first place is, to us, a far better strategy than trying to save things because they have become dire.

But wait, you say. I'm still dubious about this. Why don't you just outcross back to the German Shepherd? They look a lot like Shilohs, and that's what your breed was created from, wasn't it?

There are a few reasons that crossing to the German shepherd, and to breeds closely related to it, isn't ideal. That's the next page in this series. Read on!

• Click here to go to our next page, "Why Not a GSD?"
• Click here to return to the main Genetic Diversity page.


• Want to read more about our Genetic Diversity study with UC-Davis? You can check that out here to see what stage we're at.


• If you'd like to look at our upcoming litters, including outcross litters, you can read about them here.