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Outcrossing: Why not a GSD?

Shilohs come from GSD’s. Why don’t we just cross back to German Shepherds, and get puppies that look very similar to Shilohs? There are a few reasons that we feel this would be a step in the wrong direction.

First let’s examine the reason for using a German Shepherd for an outcross. The puppies would look roughly like Shilohs, and they might act mostly like Shilohs. That’s it, right? So really, that's making a decision purely on the basis of superficial traits. It doesn't address long-term breed health at all.

There even seems to be a misconception in some circles that Shilohs are just a different subset of German Shepherds themselves, so adding in a German Shepherd is hardly even adding a different breed. Yet, both our UC-Davis study and the Embark database have found that the above is NOT true, at least for the ISSA Shiloh Shepherds. The results have shown that our ISSA Shilohs have their own distinct genetic signature, different from German Shepherd dogs. They have become, genetically, their own thing. This is reflected in the differences in type and temperament between the two breeds.

Keeping Our Goal in Mind

At the ISSA, our goal is not to make Shilohs back into German Shepherds. Our goal is to preserve the “Shilohness” of our breed while improving health, longevity, and the ability of the breed to move forward into the future. If adding a different breed of dog makes us move away from the German Shepherd—-well, we are already genetically, structurally, and temperamentally different from the German shepherd.

Speaking of health and longevity…that brings us to point two about why we believe a German Shepherd is not the best outcross for the Shiloh.

Some research into health disorders has shown that the genes that cause a genetic disorder may differ slightly from breed to breed. In particular this has been shown for many of the genes influencing hip dysplasia (you can check out a study that references that here). It’s also the case that only a small section of breeds has been proven to benefit from the DNA test for degenerative myelopathy, or DM (you can see that list of breeds on the OFA website here). Sure, any dog can be tested for the genetic mutation, but the gene has only been tied to actual DM in that short list of breeds.

Shilohs, though, come down from mostly German Shepherds. We only separated in 1991—as of this writing, 26 years ago. This means that German Shepherds not only have all the same genetic diseases as Shilohs, but that they are almost certainly on the same genes. We have seen evidence of this in past GSD-related outcrosses, which have produced EPI, SAS, and mega-esophagus in the very first generation. In the second generation we have seen autoimmune diseases, strongly tied to lack of genetic diversity, like pannus, lupus, and cancer. These were outcrosses who were carefully chosen and researched for their health--but they were all mostly or entirely bred from German Shepherd dogs, so the diseases were able to match up. And they did.

We have a pretty healthy breed despite all this, and we really would like to improve on it. Unfortunately, German Shepherds have a very long list of genetic diseases they are prone to. There's this study that just came out of the United Kingdom, for one thing. You can see another list here, compiled from Canadian veterinary data. Now compare to the other breeds listed on that web site. Even popular breeds like Labradors have fewer listed disorders. And remember…IF all of these genetic diseases exist in Shilohs, they are likely at the same locations on the same genes as they are in GSD’s--meaning that, if we used a GSD as an outcross, we would be reinforcing these disorders in our gene pool.

In contrast, if we choose breeds who are very different from the Shiloh, we might produce some funny looking pups for a couple generations, but we are likely to get fewer genetic disorders—-AND fresh genes to hopefully give us a boost of vigor, for better immune health and longevity.

Looking Beneath the Surface

Which is what it really comes down to, in the end—-point three. The purpose of outcrossing should be to bring in genetic diversity, to improve immune system health, see stronger newborn pups, and reduce the incidence of genetic diseases. The Shiloh already comes from heavy German Shepherd lines with only a couple of other breeds mixed in. Crossing back to German Shepherds wouldn’t stand to get us many more new genes—certainly not nearly as many as going with a different breed of dog.

But what about using a GSD from another country? Well, we’ve already done that. Past outcrosses have utilized Canadian German Shepherd blood (Samson-Woo and Orbit), German GSD blood (Artus) and eastern European German Shepherd blood behind our Czechoslovakian Vlcak outcross, as well as GSD blood from different regions within the USA (Sabrina, Chani).

But couldn’t there be German Shepherd diversity out there that we don’t have? Yes, there certainly could be, but there may not be very much. Remember that German Shepherd dogs themselves descend from a relatively small pool of dogs. Recent analysis via DNA has shown that a large subset of German Shepherds are closely related to each other—another way to say that they, too, are lacking diversity. (You can read about that research--not just for the German Shepherd but for many breeds--here on the website for the Institute of Canine Biology.)

We would need to search the world for the dogs that have some bits of different genes—-but again, why should we? All dogs come down from the groups of progenitor wolves who became domesticated so long ago. Why not instead look to a breed that, though different on the outside, has what we need on the inside?

The Next Step: Know What You Have

Okay, you say. You sound like you know what you’re talking about. But what kind of research did you do in your own back yard to prove that this outcrossing is necessary? How much do you really know about the health and genetics of your pool of ISSA Shiloh shepherds today?

Read on to see all the research we did to come to a complete understanding of what we had to work with: our Outcrossing Checklist.


© 2016 International Shiloh Shepherd Alliance, Inc.