We all care about preserving our breed’s unique qualities, and the current situation with decreasing genetic diversity certainly makes the situation more challenging. It’s only natural that as we gain more knowledge and realize the need for change, we all must go through the change curve. Some of us are newer to this subject and may still be in the stage of denial or anger. Some of us are perhaps feeling depressed about the state of things. Some of us have reached the final stage of acceptance and are trying to find (new) ways of moving forward. In the Facebook group Rhodesian Ridgeback Health and Long-term Sustainable Breeding, we are happy to offer information to spread awareness and answer questions, offer support as new challenges arise, and we hope to have fruitful discussions on how to best preserve the breed-specific qualities while keeping the breed sustainable. We also want to encourage you to contribute with your knowledge or, for example, share scientific or pop-science articles on relevant topics.
It’s hard to leave behind old truths about breeding. Given the scientific data that we now have at hand, we have been taught and practised ways that may not be feasible. This is frightening, puzzling and challenging. And it’s only natural that some will resist change.
Rethinking Breeding Practices
One old truth that tends to linger, is the benefits of line breeding and many will argue that the occasional line breeding will do no harm. It will also be argued that line breeding is justified as long as you double up on sound dogs. The major problem here is that you will also double up on traits that are not yet visible and there is no way of knowing exactly what’s put into the cocktail.
Line breeding is a form of inbreeding and it’s important to acknowledge that inbreeding is a significant concern for our pure bred dogs. It’s essential to clarify certain misconceptions about using a high Coefficient of Inbreeding (COI) and the supposed benefits of inbreeding, even if it’s done occasionally.
The idea that transmitting beneficial traits while avoiding known health problems justifies a higher COI is extremely misleading. Even though it’s true that inbreeding can raise the chances of forwarding desirable traits, this practice also magnifies unseen genetic faults that may not reveal themselves immediately. Over time – generations and years – these recessive genes accumulate, leading to a heightened prevalence of serious health issues. DM, JME, and EOAD in Rhodesian Ridgebacks and LAMP3 and PLN in Airedale Terriers are recent reminders of what inbreeding generates. And let no one fool you into thinking that these diseases are unfortunate events because this is what happens when you inbreed, and I can assure you that this is not the last time we will see this happen in our breeds if measures are not taken, unfortunately.
The Reality of COI
It’s extremely important to differentiate between pedigree-based COI and genetic COI. Most often, when we talk about COI, we refer to pedigree-based COI, which is calculated from the relationships known in the dog’s family tree over a certain number of generations. This method merely observes the common ancestors in the pedigree and their recombination in the offspring but doesn’t acknowledge the actual genetic contribution from these ancestors to the dog’s DNA. In contrast, genetic COI measures the degree of homozygosity in a dog’s genome, giving a realistic view of inbreeding’s impact on the animal’s genetic health. Sadly, for Rhodesian Ridgebacks, the average genetic COI is surprisingly high at almost 20%, a level almost comparable to that of inbreeding between half-siblings or father to daughter (25%). Beyond the stage of sad to the stage of crisis stands the average Airedale Terrier worldwide with a genetic COI of around 40%. These high level of inbreeding exposes the breeds to a substantial risk for genetic health issues due to lessening genetic diversity.
Pedigree-based COI can sometimes create confusion. Supposedly, two parents could each have a pedigree-based COI of 25%, signifying heavy inbreeding. Yet, their offspring might technically have a pedigree COI of 0% if the parents, compared to each other, have an unrelated background in the 5, 8, or 10 generations you have set. But that doesn’t imply that the offspring would be free from inbreeding-associated risks, as pedigree COI does not consider the unknown recessive genes each parent might carry. Conversely, genetic COI provides a better understanding of the degree of homozygosity and connected risks.
It is also not possible to compare pedigree COI to genetic COI. For example you may have a dog with COI at about 10% in 5 generations, who in an outcrossing combination produces offspring with a COI under 1% in 5 generations. Reducing COI that much in only one generation may appear very promising. However, the mentioned example does not, in fact, ”fix” and ”improve” the inbreeding of the resulting offspring, as the offspring still carries the inbreeding of its parents, as pedigree-based COI only measures similarities between 2 parents in a certain generation interval, it does NOT take into consideration the level of inbreeding each parent carries.
Moreover – and importantly to understand – if there are common ancestors in both pedigrees, inbreeding generally rises with each generation. As an impact, each occurrence of close breeding elevates the COI, thus compromising the gene pool and intensifying the risk of inherited health issues. Over time, this cumulative effect could have grave implications for the breed’s health, rendering genetic disorders hard to eliminate.
Given that most pedigree-based COIs are calculated at 5 generations, the true increase of pedigree COI will also become masked by the addition of one generation, and thus ”ignorance” of another generation (5th generation becomes 6th generation, and are thus excluded in a 5 gen pedigree).
A Call for Change
In human beings, although close-relations marriages are legally accepted in many regions, they are typically discouraged due to the increased probability of genetic disorders. History provides examples of why this caution is necessary. For instance, rampant intermarriages in the Habsburg dynasty resulted in severe genetic issues, including the notorious “Habsburg jaw,” which led to the decline of their royal lineage. Similarly, deleterious recessive genes for hemophilia spread across Europe’s royal families due to prevalent intermarriages in Queen Victoria’s extended family.
It is imperative to understand that the impact of inbreeding is not always immediate but accumulates over time (decades or even centuries), leading to marked health crises. Given that the Rhodesian Ridgeback’s genetic diversity is already compromised, continuous breeding with elevated COI — occasional or not — worsens this problem. For a breed that’s only been around for about 100 years and is relatively young, continuous inbreeding only compounds the risks of genetic disorders and health problems being passed down through generations.
Just like cigarette smoking was once considered harmless but is now correctly identified as a major health risk, our grasp of dog breeding practices must also adapt. Practices that were once considered acceptable, like close breeding to retain specific traits, are now rightfully recognized as harmful.
If the future health and wellness of our purebred dogs is our priority, we must keep genetic diversity and long-term survival above short-term returns. It is about making sure these dogs live healthy, joyful lives for generations to come. The outlook for our dogs health consistently hinges on making breeding choices that enhance genetic diversity. If the dog is not healthy, it does not matter how the dog looks or how the dog performs its work/hunt. It is always health first. It’s not about what certain people believe, it’s a fact. As easy and that, and still so difficult to grasp. We must consider whether enhancing a specific trait is worth risking the health and future sustainability of our dogs. The stakes are too substantial to take chances. By adopting up-to-date genetic knowledge, we can make informed decisions that ensure our breed’s long-term health and viability.
We are approaching a critical point where maintaining a healthy future for our breeds is increasingly challenging. The genetic diversity of Rhodesian Ridgebacks and Airedale Terriers is so constrained that we risk reaching a bottleneck where ensuring a healthy breed might become unfeasible. I am not afraid or ashamed to say that, sooner than we might expect, cross-breeding with other breeds could become the only viable option to ensure the long-term health and sustainability of our breeds. Let’s make a joint effort to avoid this, maybe it’s not too late if we start now?
Published on the Facebook group Rhodesian Ridgeback Health and Long-term Sustainable Breeding, August 16, 2024 (link)