Dog Breeding in the Digital Age: The Results Are In! Now What?

In last week’s article, I discussed the tremendous amount of data that is now available. Yet, even though there is more information “out there” than ever before, breeding dogs has become more difficult, not easier. In this week’s article, I am going to go over strategies that breeders can use on an individual basis to cope with test results as they come in from various sources. Did I say “cope with”? Yes, I did! Read on…

In the beginning, dog breeding was as much (if not moreso) art as science. Breeders studied pedigrees, learned the prominant lines (male) and families (female) in their breeds, and which “nicked” well with each other. People did not utter words like “gene pool”, “diversity”, or “gene frequency”. While the basics of inheritance were well understood by many, it was their sense of where the good genes could be found and how to mine this knowledge which separated the great breeders from the rest.

Breeders today have to work with a great deal of information in order to come up with a breeding that they hope will contribute quality pups to the next generation. There is so much information, in fact, coming from so many diverse sources, that breeders are at risk of becoming technicians, simply breeding for a “good” test result, rather than artists looking at creating the equivalent of the next canine masterpiece. I call it the difference between negative breeding (breeding to get away from some percieved unwanted trait) and positive breeding (establishing a vision and breeding in a positive direction toward that goal).

It’s important to maintain balance in breeding decisions. Tests should not be disproportionate in the decision-making process. Tests can become the sole driving force in a breeding program; conversely, some breeders do not test at all! Neither one is conducive to producing quality animals.

Breeders need to not only have a working understanding of the diseases they are testing for, but also need to know how those diseases affect the breed as a whole (macro-scale), as well as on an individual level (micro-scale). Breeders deal with both: on the macro-scale side of things, not wanting to pass on deleterious genes to the next generation, while at the same time not damaging a breed’s diversity. On the micro-scale side, breeders need to know how to counsel puppy buyers who end up with a pup who does not get a passing test result. They also need to be able to sell pups, and promote their stud dogs! Inability to balance macro- and micro-scale effects of genetic tests creates problems in one direction or another. Too much emphasis on micro-scale, and other genetic issues for which there is no test can magnify in a breeding program. Bottlenecking and diversity can be lost if too many breeders follow the same “recipe” for breeding. Too much emphasis on the macro-scale can cause a breeder to have difficulty selling pups, or a stud dog goes unused becuse of popular perception of that breeder as a “maverick”.

So, how does a breeder or individual dog owner cope when the test results start rolling in? How to keep it all in perspective when that phone call comes in that a pup is dysplastic, has cataracts, has an unexplainable test result? This is where a breeder’s knowledge, and a breed-centered Parent Club or Breed Association can be most valuable. Every scenario is a bit different, as each type of test has a bit different approach. I am grouping these into logical (for me) groupings, rather than disease-by-disease, which would be a very long article indeed!

Polygenic diseases with no gene test: these are genetic issues that do not yet have any gene-based test for them. Instead, we do what is called a phenotype test: assessing a dog for evidence of the results of deleterious genes, rather than looking at the genes themselves. Screening tests in this category include OFA/PennHip/OVC for hips, elbows, patellas, thyroid, cardiac, shoulder OCD, and CERF screening for cataracts and entropion. Some of these tests are the oldest and most commonly used, yet the diseases they screen for are extremely complex and involve several to many genes.

My mantra for all test types is: get a second opinion! In some cases, and depending on breed (this is where info from your Breed Club would come in handy!), waiting a while before retesting could be useful. Since these tests are done by visually examining a dog or its x-rays or other imaging, human error becomes a factor. Differences in positioning, radiograpic density, and sedation all play a role in how an x-ray can turn out. Also, knowing your breed’s developmental quirks factors in. For instance, unlike the majority of breeds OFA reports on, Chessie hips can improve marginally to markably between the ages of two and four years. Waiting six months to a year and redoing films can yield vastly different results. Lastly, it’s always useful to send the films in to OFA. While your vet may be a great guy (or gal!), the OFA screens many more hips than the average vet, so while your vet may deem the x-rays as not able to pass, OFA may have a different idea on the subject.

Likewise, visually examining a dog’s eyes for evidence of hereditary diseases is fraught with error. The lighting in the exam room may not be right. The vet doing the exams may not be used to looking at your breed’s eyes. The eyes of all mammalian species actually start out as part of the skin; in some breeds (like Chessies) which have unique coat types and coloration, odd “artifacts” can remain from the embryonic development stages which can mimic a cataract. If a dog or pup is diagnosed with cataracts, waiting six months to a year and redoing the exam is the best advice. If you are relatively new to the breed, or this is your first encounter with a non-passing result, consult with other knowledgeable breeders for the name(s) of Veterinary Ophthalmologists in your region who have experience examining many Chessies.

As a breeder, when you get that phone call from a puppy buyer, don’t feel shy about asking those probing questions. These can be difficult calls to field; emotions can run high, the puppy buyer may feel used, etc. It’s a good idea to remain calm, not be accusatory, and find out the details. It could save the dog/pup in question, and salvage the breeder/buyer relationship. There are vets out there who recite the mantra that all breeders are bad and just in it for the money. If your puppy buyer has the misfortune to have one of these vets, your work is cut out for you! Have factual references you can point your puppy buyer to, like articles on the OFA website, or your breed’s Parent Club.

Single-Gene DNA-Based Tests: These are DNA-based, true “genetic” tests which look at disorders which are caused by one gene, rather than several genes acting together. In Chessies, these diseases include prcd-PRA, EIC, ED/SF and MPS-VI. “OK smarty-pants” I hear you say, “how does a second opinion apply HERE?” Here’s how.

All DNA-based tests rely on sampling the pup or dog in question. They also rely on laboratory testing of those samples, and accurately documenting and recording those results. There is room for error at both ends of this process.

When sampling for DNA, a blood draw is always the gold standard. Cheek swabs are efective, but it’s too easy to get samples mixed, especially where litters of pups are concerned. Puppies swap spit all the time! Add in the fact that in many cases, owners take their own samples, and the chances for error multiply. In any case where a test result is from a litter of pups sent in by the breeder, it is prudent to have the test redone via blood draw (if possible) or have your vet do the cheek swab following the mouth cleaning protocol to the letter. Yes, retesting DNA is expensive, but not as expensive as spaying/neutering an otherwise perfectly good dog.

At the other end of the process is the laboratory doing the testing. Yes, there are many labs out there offering testing, sometimes at a greatly reduced rate. There is nothing wrong with seeking some overhead reduction, but just be aware that some labs are using earlier or incomplete versions of the tests available. Results may not be accurate, and you may have to suffer the embarrassment of explaining how a pup could test “affected” when both parents tested “clear”. To be on the safe side, I recommend that the DNA Labs listed on OFA’s site be used. This will save you the expense of retesting at a later date if/when inconsistent results crop up.

Next week, I will tackle DNA Tests for Polygenic Traits, a unique (and still fairly new) category of testing, that is causing headaches and waves of anxiety throughout the dog-breeding community. Not to mention, posing a real threat to purebred dog breeding, worldwide!

 

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Dog Breeding in the Digital Age, Part One: A Flood of Biblical Proportions

This is the first in a series of articles dealing with the challenges that modern dog breeders (and puppy buyers) face in the digital age. From new DNA tests, to the scores of websites tabulating data and factoids (more about this in a later article), to social media, dog breeders and buyers are bombarded with information.

While I believe in the free exchange of information (after all, that is why ChessieInfo was created), when that information is decentralized, disorganized, incomplete, incorrect, not explained well, or not put into context, it is as good as useless. People need to be able to make sense of the information they see every day.

Most dog breeders are not scientific researchers. Most researchers are not dog breeders. The future of purebred dogs lies in the gap, which is very wide. Add to this the fact that most breeders are extremely small-scale (one, maybe two bitches), and that gossip is the lingua franca of dog sports, and you have a recipe for disaster. Let’s look at the historical perspective, which gave rise to the analysis paralysis that dog breeders are currently experiencing.

In the late 1960s, something new was developed. It was a way for those breeding functional working dogs to detect and attempt to reduce the incidence of a crippling disease known as hip dyaplasia. It was a simple paradigm, and most everyone was willing to climb aboard. Just x-ray your breeding stock, spay/neuter those that didn’t have good x-rays, and breed the rest. Simple. Parent Clubs published articles about how hip dysplasia could be reduced. Advertising in some breeds was restricted to only those with a hip clearance number. In some countries, only dogs with a certain hip grade or higher were even allowed to produce registerable litters. A culture of peer pressure was developed, and because there was only the one “genetic” (really, only phenotype) test, it was simple to adhere to, and almost everyone climbed on board.

Then a few years later, another certification was added: eye exams. Now we could x-ray hips, *and* certify that our dogs were free of eye diseases like PRA and cataracts. The “test and eradicate” culture that already existed regarding hips shifted to this new test: now dogs had to have a hip number and an eye number. But still, with only two tests, it was pretty simple to adhere to. This continued for more than two decades, and became the norm. Keep in mind, most people stay in the dog game for five years or so, so by the time the third test (for elbows) came along in the early 1990s, these certifications were “the way it’s always been” from the perspective of most breeders.

The first DNA-based (truly genetic) test was released commercially in 1999. Since then, the number of tests available for breeders has blossomed…erupted…into a flood of tests. Some breeds have relatively few. Some have many. Some tests are gene tests, while others are phenotype tests. Some test for single-gene traits, while others look for one gene of a polygenic disease. In Chesapeake Bay Retrievers alone, there are tests for hips, elbows, eyes, patellas, shoulder OCD, thyroid hormone levels, cardiac abnormalities, and  von Willebrand’s disease. All of these are phenotype tests. Then we have the true genetic tests: prcd-PRA, Degenerative Myelopathy, Exercise Induced Collapse, Mucopolysaccharidosis-Type VI (a storage disease) and ED/SF, a rare skin disorder. A test for dwarfism is being developed, and one for epilepsy may have use in Chessies. New PRA tests have also been developed, and it may well be the case that a second or even third type of PRA, while rare, exists in the breed.

The things we test for, how we are testing (looking at DNA, not just at the results of the DNA), and how much we are testing, have all changed. What has not changed is the culture. There still exists the mentality that a dog must “pass” before it can be bred. Or if (heaven forbid) a dog that is a “carrier” is bred, it must only be bred to a tested “clear”. This mindset, and the peer pressure/rumor mills that accompany it (magnified by the use of social media) can be extremely destructive to the production of high-quality, overall healthy animals. Does this sound contradictory to you? After all, breeding to tested clears should reduce the number of carriers, right? Isn’t that the point? “And Lisa,” I hear you say “even the researchers say on their websites that carriers should only be bred to clears.” Let’s look at the bigger picture again.

Why do we have all these genetic tests all of a sudden? It seems like new ones come out almost every day. Where is this all coming from? And more importantly, where is it all headed? The completion of the genome for humans, dogs, and mice has led to an amazing discovery: dogs have many of the same genetic diseases as humans, caused by the same genes. This means that researchers studying say, bone cancer, can use dogs in their research. Dogs have a short breeding cycle, mature quickly, and are easy to get DNA samples from. They are also easy to work with, and (lo and behold!) have breeders who will line up to donate samples to any research project. The research team does not even need to bear the costs of housing, feeding, and caring for experimental animals. This makes for a mutually beneficial situation, where human research needs generate funds that dog breeders, even large Parent Clubs, would not normally be able to afford. In the mean time, there is a large population of test subjects available to research teams. In this climate, as genes are identified in dogs, and cross-mapped so that human genetics can be better understood, new gene tests which can benefit our dogs are also developed. The number of DNA-based tests will skyrocket. It will never get smaller.

As each new test is developed, the decision process for breeders becomes more complex. Remember what I said earlier about researchers not being dog breeders? They are looking at their tiny slice of the pie. Of course, if *their* particular test was the only test in existence, *and* it is a low gene-frequency type of trait, breeding carrier or affected/at-risk to clear is a no-brainer. However, with a number of tests now being done on each dog, it becomes harder and harder to find a dog that tests clear for everything that our bitch does not, *and* also (incidentally, um, tell me again why we breed dogs?) actually complements her! All dogs are carriers for many diseases. The more tests that are developed, the harder it becomes to weave our way around the genetic obstacles. In Chessies, we have already reached the tipping point.

It is difficult to breed dogs when one is limited to only one or two breedable bitches. Sometimes, one has to make a tough decision to do a breeding, even though that breeding may be carrier x carrier. It is very hard to breed good dogs without making some concessions along the way. By breeding only to tested clear dogs, you are automatically limiting your selection of potential stud dogs to that smaller group. If your bitch is a carrier for two different things, the selection is even smaller. And what if your choices are dogs that simply will not help your breeding program? What if you breed your carrier bitch to a stud who is not the best choice for her, and the pups turn out to be lesser quality than your bitch AND all carriers anyway (this has happened already…more than once)? Are we breeding fir quality dogs, or are we breeding for test results? The decision lies with each of us, and we should not be overly critical of those who make different choices than we might. After all, genetic diversity is maintained by individual breeders making selection choices that vary from what other individuals select on. If everyone breeds dogs along the same “recipe”, genetic diversity becomes irreparably lost, and quality suffers.

 

 

 

 

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ChessieInfo Blog

This is a new feature on ChessieInfo…blogging…? Something new for me as well.

This space will be used for short articles on dog-related topics, particularly those of interest to retrievers and other gundogs in general, and Chessies specifically. Feel free to suggest topics. I will do the research and the writeup!

 

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