|Breeding for Disease Control, Longevity and Temperament
JP Yousha, Chmn. Health & Welfare Committee, GDCA.
Subject: Breeding for Inherited Traits: Avoiding Disease. Part One.
This article started as a casual, online conversation on one of the Dane Lists. I simply thought I would post up a couple of links and a couple of quick comments about "genetic" disease (as people say), because there seemed to still be some misconceptions widely held about it, but the discussion grew and this article grew out of it. It's still in the format of a casual conversation & should be read as that: less formal and exact and more broad strokes to drive home major points. It goes without saying (hopefully) also that this is about basics, so is preaching to the choir where many readers are concerned. But important topics need to be regularly revisited?
Just start with the term "genetic disease" as an example; all disease in a sense is genetic as it all involves genes. But people seem to think of disease that involves genes as automatically inherited and that simply isn't so. Inherited implies, for a breeder, some potential for control arguably can exist through the choice of breeding stock. And it's just not the case that disease either can be split into neat categories of "genetic" (inherited) and "environmental." Such categories don't really exist in the biological world, and this isn't anyway what is a breeder's focus when choosing bloodstock & planning breedings. The idea rather would be to focus on what seems to offer some control as to traits, and in the case of disease, to screen against them, focusing on both how to gain control and a priority system of what is most important to strongly select against. "Genetic" disease, more accurately referred to as heritable, or inherited, disease is being defined simply as disease that is directly inherited and/or disease with a strong heritable component, so that avoiding disease becomes, in part, a matter of breeder choices as, at least partially then, under a breeder's control. As I said, there seems to still be some widespread misconceptions out there about inherited disease.
I started thinking about this lately as I find it worrisome now to see now websites touting out crossing as some formula for health--just like you used to see line breeding offered as some formula for type. Such generalizations and "recipe breeding" just don't work: you have to make yourself clearly and completely aware of not just sire and dam, but the family, writ large, of the dogs you are dealing with. That's why it's sad to see someone admitting to type problems, saying they are importing dogs to outcross as they "believe" it confers better health (and/or temperament). Breeding to dogs with admitted shortcomings that you have never seen is no way to end up with good dogs--no matter how you define it. And such a "recipe" isn't going to confer health anymore than breeding any relative of a famous dog to another of the same family is going to guarantee type.
What people may not know is there is such a thing as *out breeding depression* just like there can be inbreeding depression. With inbreeding depression, typically you will see two sorts of results. On one hand recessive traits come to the fore, be they odd colors or things like Wobblers & mega. The other thing you see is a general tendency to smaller litters, smaller size, and lessened fertility as well as a general lack of thrift. In other words, you end up with "poor doers"--dogs who are fragile or fiddly--when you depend on line breeding too much, do it indiscriminately, and/or you are not "minding the store" when line breeding (as in knowing what skeletons lurk in your family closet). When things like this start to accumulate, you simply have to "let some air in" to a closed pedigree and/or you have to be more selective in what animals you are choosing; not using some dog simply because he finished or his dad did well, especially if you are having to rationalize a dog who did well in one way (say showing) while he has other problems that are line-related. Line breeding isn't something to do blindly.
But some diseases, particularly complex traits like involve CHD (hip dysphasia) you can actually get by out crossing. Why? Because one you are "breaking up a good set" of genes that has been working for you and your dogs. Secondly you are importing, wholesale, in an outcross, a set of foreign genes at times, and they may also work on their own, but not when they are broken up and mixed with in your dogs. These sorts of situations are called threshold diseases, and the gene expression term used is "cumulative traits." Things like size in a line, head type, organ and joint structure are very often a result of such cumulative traits. Cumulative traits are, grossly speaking, the result of a bunch of the "right" genes coming together, not of any one "good" or "bad" gene. So with cumulative traits the best breeding strategy is typically one of avoiding extremes. You stick with the middle and don't confuse moderate with mediocre. And so, by avoiding extremes, you collect up the most of the genes that work well together, giving you what you want to keep seeing.
That also means you must recognize every dog isn't going to always be ideal to be useful to your breeding program. What I mean by that is that, for example, if you have a family of dogs who are all checked and all passing OFA, you avoid dogs then that fail and/or who develop CHD (the extreme), but you can use dogs who are not Excellent, as they likely have nearly the same set of genes for this cumulative trait as does the Excellent individual. Or, another example, you want good size, so you use some moderate sized dogs, but not really tiny little bitches. Avoid extremes, but don't go overboard looking for "just the right" (ideal) dog is the idea with cumulative traits. Out crossing in this case (and temperament is another area of complex inheritance) is arguably more likely to be hurtful than helpful, unless you really know that other family well indeed. Take home message: different strategies for different genes.
And the strategy is again different for traits that are hybrid traits (like Harlequin color) or X-linked (like Dane DCM). You simply cannot just make blanket statements (line breeding or out crossing is good or is bad), or breed "paper tigers" (to dogs you don't know who are to you "famous names" or "has health checks on their dogs") and expect success. There are so many new breeders out there these days, and seems there are more and more every day. Many also starting out anymore tend to be "independents" that may have purchased a dog or bitch from here or there, but are not aligned with any one breeding program or have a specific mentor.
That can create problems as there then isn't always access to a good body of knowledge about the dogs and the history of the breed, and then this results in folks having to "learn by doing;" by which I mean having litters with problems that another more experienced breeder could have seen was a decided risk in the planning stage. No one creates problems of any kind on purpose. But as the road to hell is paved with good intentions, in this world of dog breeding, ignorance has probably spawned more tragedy than pure evil. None of us wants to have to say: "I wish I'd known," when another can fairly answer: "Really, you should have."
Also doing disease screenings ("health checks") is great, but these tests also have to be used knowledgeably. For example, the OFA Cardiac does NOT screen for DCM or SAS. And doing a thyroid check without a TgAA is pointless on young breed stock, while doing an initial screening is fine, but it's no declaration that the same dog, when 4-6 years, is still thyroid normal. A CHIC dog with all passes can later gets thyroid disease or comes down with Addison's, just as an untested dog who is declared "healthy" can mean nothing more than the owner isn't unhappy with the dog. And that doesn't mean the dog doesn't have things that would trouble you. And often checking for disease is still about considering relatives and knowing your pedigrees. A DCM carrier bitch is never going to show any signs of what she inherited, but she will still pass this deadly disease on to her sons and daughters. If you didn't know her dam's sire died of DCM you are going to be surprised when her son does. We cannot be "one trick ponies" when breeding--we must "multi-task" in the sense of juggling all the issues (health, temperament, type, structure, gene load) involved. And we need to sort this, as no dog is going to have it all. So you have to prioritize. And for disease, this is going to mean strongly selecting against inherited diseases that are (a) deadly, (b) serious & chronic, and (c) costly to manage. Plus a priority has to be set to screen against adult-onset diseases, as these are likely to "show" after you have bred. Especially in Danes where some of our large problems *do* only show up in the middle years. So this again illustrates just how important it is to first (1) know your pedigrees as more than names and titles, and then (2) be knowledgeable about what is the best strategy of control for each kind of inherited disease.
To that end, here are some links on how to assess the risk & do a risk: benefit analysis and relative risk assessment of various problems (below). And I am always available to help with these relative risk analyses to those that want a consult. This is done with full confidentiality of course. Links:
Subject: Breeding for Inherited Traits: Longevity & Temperament. Part Two.
Well I never thought this would be so popular, but have been asked for several reprints of what is now "Part One" of this article, and I have been asked to also talk a bit about "breeding for longevity" and "breeding for temperament" as issues. So I will. But first let me say I am (a) acutely aware I am preaching to the choir here, as many of you know all this, and (b) painfully cognizant of there being many more experienced than me in the audience who could do a better job of summarizing this stuff that mere "moi"- I stand "on the shoulders of giants" as they say....and I use their words. This is wisdom I was gifted with, so don't think for a second I am thinking I'm some genius. A parrot is closer to the truth!
That said (so my betters don't think I'm some arrogant upstart), more on this topic we all need to face. First off, let's face the sheer ugly fact that some breeders and especially some Internet sites are "front & center" saying they breed for longevity and/or temperament as pure sales technique. No quality show breeder with gobs of type is necessarily not also getting tons of robust and happy dogs: it's not an "either-or" situation and NEVER (EVER!) should be. All areas (i.e. health, temperament, type) count, and the main issues in them are ALL important & have to be considered: no one-trick ponies, right?
First to speak to this question of longevity; one of the most annoying things I think we have all seen is this sort of claim that "my dogs live longer than yours," with very weird quotes of age ranges as average life spans and other improbable stuff. If you are really worried about longevity (and shouldn't we all be; I bet we all are?), then the first thing you do is TRACK your dogs, carefully noting COD (cause of death), along with the date/age, for EVERY DOG (not just parents) in at least the three generations behind what you are now breeding. Yep, that's hard and likely impossible to always accomplish, but still a good goal to shoot for? Until you know how the dogs behind your dogs lived and died, how can you claim you have some trait--any trait at all? Secondly we all have to realize what is and isn't reasonable for a giant dog. To expect a decade of healthy living from a giant is to recognize their natural life span. To claim a lot more or allow a lot less, saying they all should live to 12-14 or all can die at 6-8, is not reasonable.
Thirdly, we have to realize in this breed we have a problem with ADULT ONSET DISEASE. We could talk about this for about 10 hours, but the bottom line with such disease is (a) you need to have quality pedigree info, i.e. you need to know how the dogs behind yours lived and died, and (b) you need to extend your generational period as much as possible. This just means you try to have a 3-4 (or more) year gap between dogs and their offspring, as opposed to breeding a lot of very young animals. This is just logical, for, if your breed is likely to manifest serious disease between 3-6 years, and you do the bulk of your breeding before that, it doesn't take a rocket scientist to figure out you are going to be too often stuck trying to shut the proverbial barn door after the horses have left the building. That's why modern science created the frozen sperm? And that's why a lot of old-fashioned breeders prefer to use older stud dogs, especially when going out of their own family of dogs.
This issue of temperament has already in a way been addressed, if just briefly, in Part One. Recall this is a, bluntly, a cumulative trait ( it's actually a cluster of such traits, but never mind that tangle for this discussion). The bottom line then is you have to avoid extremes. We are facing a serious problem with temperament in this breed. Maybe it's always been there; there sure are enough anecdotal reports, but the latest GDCA health survey found that ~25% of respondents were reporting SERIOUS temperament problems in the dogs they owned. Now with a 150 lb. dog any real problem is going to be serious in a way that the same problem may not be in a dog of 15 lbs. But that doesn't change what we are facing. We have two extremes to avoid, that of very shy dogs (those "freaky Jeans" who have unreasonably panicky reactions to every day things) and the very tough dogs (which we called in GSDs "espresso" as they were so strong natured you felt they sometimes looked at you like you might not be able to take them). I wonder at times about us as Great Dane people; this is a working breed and yet as a group we don't seem to know much about dog temperament, and often simply talk, very naively, of "good" & "bad" temperament. Temperament doesn't work this way.
Temperament, in a sense, is more like the thermostat on your heating unit: it has a range and can slide a bit either way. The range is likely inborn and the early upbringing then sets the exact "degree." Some dogs have what GSD people call "weak nerves" and simply have trouble handling everyday events. If you think about it, temperament in this sense is just another body system, with the nervous system at it's core. So to be pathologically shy is just the "un-nice" extreme of a sweet and biddable pup. And to be predacious, or dog/people aggressive, is just high-drive, good working dogs....gone bad. Avoiding rationalizations and the breeding of these extreme dogs is the key to having most all of them turn out to be livable. There is a lot more to be said on the subtle variations of temperament, but I am truly always in trouble for handing out too much information, so I will stop. But really, we ought to become more interested in this topic? For one thing every dog has a job to do; even being a "couch potato" is an occupation of sorts; so every dog should be expected to demonstrate correct temperament for his work. And another good reason to look deeper into what makes up temperament is we seem to be in trouble in this area, so it would behoove us all to learn a bit more about what makes one dog mentally different than the next.
It's an odd day and age in dogs. Gone are the old allegiances. If you are quiet long enough and listen very carefully, you can still hear, softly, some of the greats talking. But otherwise you are stuck figuring things out for yourself. So therefore we all need to become very good, even very aggressive and self motivated students of the breed. Nothing's going to be handed to you, that's for sure. And the only other choice to seems to be getting stuck listening to middle-rankers like me palely echo what better minds have already said. For at best all I am still trying to be a good student of the breed....to listen up…and keep learning. And this article comes with a warning. It's fairly superficial as it's deliberately painting with a broad brush to make some basic points. It's less to pass on great wisdom and more just intended to get us all thinking...and talking a bit. I know it's helped me, so thanks to you all for giving me this opportunity to put my thoughts in order! JP Yousha/2005
This message written and prepared by JP Yousha for the purposes of education. All copyrights © remain with the author. However the author is willing to allow reprints upon request for educational purposes.