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The "catastrophe" of cross-breeding: meet the Borgis

2/22/2022

By Carol Beuchat PhD

There is growing recognition that loss of genetic diversity from the gene pool of a breed over the generations is having the unwelcome result of increasing the burden of health issues. The geneticists claim that the remedy for this is crossbreeding that will introduce new diversity into the breed. However, there is much fear among breeders that cross-breeding might improve genetic diversity, but it will destroy breed type.

Let's have a look the results of a breeding program that did a cross that most would think is crazy, of a Boxer to a Pembroke Corgi.

(This material (photos and colored text) is from the website of the late Dr. Bruce Cattanach, of Steynmere Boxers.)

When it became clear that tail docking was likely to be banned in the UK, Dr Bruce Cattanach, a boxer breeder and geneticist, undertook an experiment to see if he could produce Boxers with naturally bobbed tails. He knew that the bobbed tail in the Pembroke Corgi was the result of a single dominant gene, which meant that it should be possible to do a breed cross that would produce Boxers with naturally bobbed tails. The Corgi's longer coat and short legs were inherited as dominants, so it would be easy to remove puppies carrying those genes after the first cross.

Cattanach wasn't worried about the fact that the Corgi was so different in structure to the Boxer. In fact, he said that "In the series of backcrosses planned, it should not matter what I started with. Unwanted characteristics of whatever nature would all be diluted out, generation by generation."

"Nevertheless, quite apart from these two genes, I was hugely surprised at just how easy it was to get back to Boxer appearance by repeated crossing to Boxer after the initial Corgi cross."

The Boxer x Corgi Crossbreeding

"A ﬁrst prediction from crossing of two breeds (Fig. 1) is that, barring the segregation of individual genes in each breed, eg red versus brindle, all the progeny should look alike. But, what else could be expected?

1. Corgis have a fawn colour with the same genetic basis as Boxers, but they differ with regard to several known genes;

2. the white markings are caused by a different form of the gene responsible for whites and white markings in Boxers;

3. the legs are short (dominant);

4. the coat is long relative to that of the Boxer (supposedly dominant);

5. the ears are erect (supposedly recessive);

6. Corgis do not have the black masking factor (dominant); and ﬁnally,

7. the Corgi used in the cross had a single dose of the bob-tail gene (dominant).

The Corgi-Boxer crossbreds were therefore expected not only to be uniform in appearance; they should be fawn, have intermediate near-50:50 levels of white markings (piebald), perhaps show a black mask (dependent upon white markings), have short legs, a longish coat, and drop ears, but the bob-tail gene was expected to segregate such that only half the puppies would have bob-tails. Beyond this, the unique head features of the Boxer might be expected to give way to the more normal Corgi head."

Cattanach bred a white Boxer named Polly to a Pembroke Corgi with a natural bobbed tail. They produced a litter of seven puppies that all looked alike, with a fawn color and piebald white markings, and traces of a black mask on some. Five had bobbed tails of various lengths and two had normal tails. In structural traits, the Corgi influence predominated. The legs were short and coats longish, reflecting the influence of those dominant genes. The head resembled that of the Corgi, but with drop ears ( at 7 months the ears of one pup were erect) and eyes more like those of a Boxer. These pups were dubbed the "Borgies" and apparently were unbearably cute.

The F1 Hybrid x Boxer Backcross

"As both the crossbred dams and Boxer sire were fawn, all the pups were expected to be likewise, and all should have dominant black mask of the Boxer. However, all the main Corgi-Boxer differences (leg length, coat length, ear carriage) as well as tail type should separate out among the offspring. Moreover, because the Boxer sire, Foreign Service, carries the gene for white and the crossbreds carry both the Boxer and Corgi forms of the gene, further complexity regarding white markings was anticipated. It is perhaps best to present the expected outcomes in terms of the odds of their occurrence:

1. To take the project into the next generation, and also for practical and economic reasons, it was necessary to keep a bitch. Therefore, from the 16 puppies obtained in the backcross, only 8 on average might be expected to be bitches.

2. Any bitch to be of use for further breeding must, of course, have a bob-tail. Therefore, with a dominant inheritance, it could be expected that only half the pups would inherit the gene from their crossbred dams. Thus, of the possible 8 bitches, perhaps only 4 could be expected to have bob-tails.

3. Because of all the difficulties in mating short and long legged dogs, I desperately wanted any bob-tail bitch which I was lucky enough to get to have long legs. Again, only half of the possible 4 of interest might have this characteristic; maybe 2 out the original 16!

4. Then there was the coat length; only half again. Therefore, if I wanted to the short coat too, there would be only 1 chance in 16 of getting the combination wanted, a bitch with bob-tail, long legs and short coat. And this is without the white markings problem. Adding this:

a. one-quarter of the pups were expected to be white, with the risk of deafness that this would entail;

b. one-quarter were expected to show the piebald level of white marking like the crossbred dams;

c. one-quarter were expected to have flashy white markings like the sire; and,

d. one-quarter were expected to be near-solid, but carry the gene for the Corgi type of white markings.

Two of the female hybrid pups, Dolly and Tess, were chosen to be backcrossed to one of Cattanach's male Boxers. They produced 9 and 7 puppies respectively. These varied from Boxer-like to "Borgi", with legs of varying length and about half with bobbed tails (7 of 16).

"In all, the base colour was fawn with black mask. The white markings were of the four expected types. Two pups were white, 4 were of the piebald type, 8 were flashy and 2 were near-solid.

However, what stunned us most was that some of the pups looked like pure bred Boxers of pick of litter quality (Fig.9)."

"The surprising discovery at this stage was that few genes seem to distinguish two such diverse breeds as the Boxer and Corgi. Apart from those concerned with head properties, these speciﬁcally include those for leg and coat length.

The presence of ﬁner points that distinguish the Boxer from other breeds could still be said to be variably evident however.

Thus, so far as even the most Boxer-like dogs from the ﬁrst backcross were concerned, there still seemed to be something foreign about them. In the case of Jane, further development of head was required, she needed a larger eye, stronger and harder musculation, a shorter, harder coat and more bone. So, further improvements were needed, but perhaps little more than those involved in the ordinary task of trying to breed good show animals.

Fortuitously, because of the dominant inheritance of the main unwanted characteristics (short legs and long coat), there was no need to worry about these appearing in Jane's descendants. She had the long legs and a short coat and therefore did not carry the short leg and long coat genes, and so could not transmit them. All that needed to be done was to breed selectively over a further generation or two of backcrossing the bob-tail gene into the Boxer to create a bob-tailed but otherwise typical "Boxer". And, this might be achieved in a single further generation, with a judicious choice of sire and a little bit of luck."

The Second Backcross

For the second backcross, a solid white female was chosen from the first backcross puppies as carrying the best suite of Boxer traits. The sire had to have good type but also no risk of producing white puppies that could potentially be deaf, so it could not carry the gene that produces the white "flash" markings on most show dogs. With this dog, Cattanach then predicted what to expect in the progeny that would be produced from a cross to Jane, the typiest of the first generation backcross puppies:

"1. all the pups should be coloured and have flashy white markings within the recognised Boxer range. There would be no whites, solids or piebalds;

2. half the litter should be brindle like the sire and half should be red/fawn, Chief being a carrier of red and Jane being a red/fawn "under" the white, as indicated by her two tiny spots of red/fawn coat;

3. half the litter should inherit the bob-tail gene from Jane and be bob-tails, while the rest would have normal length tails;

4. all the pups should look like Boxers, with no "throwbacks" to the dominant Corgi characteristics (short legs, long coat); and,

5. head types, hopefully, would be much improved and, barring any total surprises, these should fall within the range exhibited by the parents."

The second backcross produced eight puppies, seven of which survived, and all with flashy white markings. Five had bob tails and the tails of the rest were normal. Cattanach said of these that "In general appearance they all looked like Boxers."

"Boxer type prevails (Figs 19 & 20 above). All have long straight legs, short backs and short coats. There is nothing foreign in their build to suggest Corgi in their ancestry...Heads, however, betray them, but only when considered as a litter. Some have Boxer heads of a standard that at this age one would be pleased to have in any Boxer litter. Thus, two have extremely short deep heads that surely derive from the Continental Boxer background, while a third has a ﬁner skull, yet with great muzzle development and with a really beautiful eye (Fig. 21).

Only one in fact has a longer head somewhat pointy muzzle that has some suggestion of Corgi. The heads of the remaining three puppies fall between the two extremes but, despite some inadequacy of stop, this would never identify them as other than purebred Boxers...Beyond this, all of the puppies have the undershot jaw, which will not alter, and several have extraordinary, wide, straight mouths which are better than commonly seen in Boxer pups. Maybe this will stay. And eye size looks very good...Of more importance is the development of the bob-tails. Here, I have to express a little disappointment. While two pups have acceptable short tails like their dam, with just a dip at the end attributable to soft tissue and hair, which could be trimmed, the other two each have a deﬁnite tail kink (Fig. 23). Despite this additional feature, I think it can still be fairly claimed that one of the original objectives has just about been achieved. We now have several 'bob-tail Boxers' of potential show quality. Time will decide whether the latter is really true."

These are the seven pups from the second backcross litter at 10 months. Four of these inherited bob tails; the rest were docked.

The Third Backcross

For the fourth generation, the best male from the second backcross litter was bred to a bitch that produced a puppy that, apart from a long tail, Cattanach judged to look like a pure Boxer.

At the end of the project, Cattanach provided the details of all of the breedings to the UK Kennel Club with a request to consider them for registration. The KC agreed to register the fourth generation as Boxers and the previous ones as crossbreds.

Descendants of Cattanach's bobtail Boxer breeding experiment can be seen in the European show ring today.

The "catastophe" of the Corgi x Boxer cossbreeding project

How was it possible to cross a Corgi with a Boxer and get puppies with good Boxer type so quickly? Look at the genetics.

The Corgi x Boxer cross produces puppies that are 50% Corgi and 50% Boxer genes (inheriting one chromosome from each parent), the "Borgies". The gene for short legs is dominant, so they are all short. In the first backcross, the puppies will pick up more Boxer alleles, averaging 75% Boxer and 25% Corgi. Depending on which alleles each pup inherits from each parent, the traits in these puppies can vary widely, some looking much like Boxers. Among these was Jane, a white bitch with very good Boxer type that Cattanach used for the next backcross. As expected, if the best of the pups from the first backcross is crossed again to a Boxer, there should be much uniformity among the pups because now they carry on average 87.5% Boxer alleles and only 12.5% from their Corgi ancestor. These dogs looked like Boxers.

This is not the catastrophic genetic mish-mash many breeders fear will be the result of a cross-breeding. With some basic knowledge of a few key genes, Cattanach was able to predict what each cross would produce. This allowed him to get quickly from initial breed cross to producing entire litters of dogs of that are unmistakably Boxers, with no hint of their cross-bred ancestry, and some even of show quality.

Cattanach was interested in transferring only a single gene, and his breeding strategy was centered on that. He was able to make progress quickly in this project because he knew that the traits that made the Corgi look so different from the Boxer would be easy to select away from. A breeder would use a different breeding strategy if the goal was to improve genetic diversity, but the same principles would apply.

The dog fancy is facing unprecedented challenges to improve the health of purebred dogs. These problems can be traced to the imposition of a closed gene pool on the population and selection for traits that compromise health. Because inbreeding is so high in all but a few breeds, improving health using selection within the existing gene pool is simply not possible. You can't solve a health problem by selection if the alleles you need are no longer in the gene pool. The only option at that point is to restore the genetic diversity of the gene pool of each breed by crossing with dogs that carry the needed variation. There really is no other way to do this. And as this experiment shows, the result will not be a breed-destroying catastrophe if done with proper planning. Take the time to understand the genetics and seek the guidance of experts that can map out a breeding strategy that will get you from cross to show quality dogs in the shortest number of generations.

If your breed has high inbreeding (okay, Sloughi, you're good; this is for the rest of you), crossbreeding can restore the genetic diversity that has been lost over the generations. Let go of fear and believe in genetics.

What about registering the puppies? Cattanach was able to register his by request. These days, the kennel clubs are under the gun to improve health "or else" (see the court case in Norway). Because there is no other way to do this than crossbreeding in most breeds, I expect there will be little resistance to registering puppies that descend from crossbreeding programs in the future.

There are a few other examples of crossbreeding programs in dogs that I will be summarizing as well. I will post links here when those are available.

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We need a Mayo Clinic for dog breeds

2/20/2022

By Carol Beuchat PhD

The Mayo Clinic is a non-profit medical institution in the United States that is famous for its integrated approach to solving difficult medical problems. Patients at the Mayo Clinic have usually run a gauntlet of medical specialists without success at cure, treatment, or even diagnosis. For these individuals, the Mayo Clinic is a last hope.

The Mayo Clinic is well known because it has been exceptionally good at solving the problems of the most difficult patients. It does this using an integrative approach to health care that might involve specialists in many fields that work together as a team to achieve diagnosis and treatment when specialists working independently have failed. Their extraordinary success using this integrated approach draws patients from around the world.

I think we need something comparable to the Mayo Clinic to help us address the growing burden of health issues in purebred dogs. Here's why.

Purebred dogs are plagued with a list of genetic disorders that numbers in the hundreds and grows longer every year. The costs to owners for veterinary treatment of breeds with high risk of disease are huge and growing, while at the same time millions of dollars are invested in research to understand, treat, or prevent these diseases. This burden of pain and suffering due to disease has caught the attention of animal welfare groups in several European countries, where legislation is being enforced that will restrict breeding of dogs that are likely to produce offspring with serious health issues. Norway has recently banned the breeding of English Bulldogs and Cavalier King Charles Spaniels in response to a lawsuit by an animal welfare group (scroll down the page at the link for English) on the grounds that the disorders common in the breeds cause a level of pain and suffering that violates Norway's Animal Welfare Act. For Bulldogs, the biggest problem is their brachycephalic skull (flattened face), which makes breathing difficult due Brachycephalic Obstructive Airway Sydrome (BOAS). It is likely that additional breeds will be added to those seen to be in violation of Norway's animal welfare laws. Furthermore, because there is similar legislation to protect the welfare of animals in countries around the world, the potential ramifications of enacting breeding bans on specific breeds are huge.

Breeding bans for violations of animal welfare laws are not designed to address the underlying problem, which is the high burden of diseases in purebred dogs. They simply prevent the production of animals that are likely to suffer. Managing and eliminating the health issues is left to breeders and purebred dog organizations such as kennel clubs. However, breeders lack the expertise, and often the will, to address these problems effectively. For example, breeders have been enthusiastic adopters of DNA testing to identify known mutations in their breeding stock, but the common assertion that a dog is healthy if it is "clear" of mutations is untrue. Furthermore, using this information properly can be tricky (e.g., mutation vs linkage tests), and advice from fellow breeders on Facebook can run the gamut from factual and informative to just plain wrong. In any case, because dogs surely have many more mutations than we know about and can test for, DNA testing will not make dogs healthier because they are so specific. For instance, a breeder that dutifully runs the available mutation tests, then produces a litter with a COI of 30%, is simply exchanging known risks with unknown ones.

Faced with a health issue, the temptation of breeders is usually to assume that it is caused by a gene, with the result that they identify individual issues and search for solutions, one problem at a time. If a genetic disorder pops up in a breed, the scenario would be to search for the mutation, develop a mutation test that can be used on individual dogs, then avoid breeding dogs together that share the same mutations. This strategy can be effective if the disorder is caused by a single recessive mutation, but many problems are not; for these, affected animals and maybe also their relatives are removed from the breeding population on the assumption that there is some underlying genetic cause that should not be perpetuated. Breeders have been trying to manage many disorders this way, such as epilepsy, cancer, and renal dysplasia, but with little success. The consequence is that dogs (and their genes) are removed from the breeding stock, which reduces the size of the breeding population and increases the rate of inbreeding, both of which act to increase the expression of genetic disorders. Thus, breeds are stuck in a loop in which the actions of breeders to reduce the risk of genetic disorders actually increases the likelihood that some other issue will appear. It's an endless game of genetic whack-a-mole that is slowly driving breeds closer and closer to point where genetic deterioration will be severe enough that the breed goes extinct.

There are breeds that appear to already be at this extinction point. A very high percentage of Dobermans die of fatal DCM (degenerative cardiomyopathy), and recently the trend has been towards deaths in younger and younger dogs. Flatcoated Retrievers and Bernese Mountain Dogs rarely live past middle age, because they are stricken down by cancer. Most Cavalier King Charles Spaniels will suffer from mitral valve disease, and an early onset form of the disease takes dogs in their prime (Lewis et al 2011). Upwards of 70% of Cavaliers are also the victims of painful neurological conditions, Syringomyelia and Chiari Formation, which are also becoming increasingly common in other breeds with shortened muzzles and a tendency towards domed skulls (e.g., French Bulldogs, Brussels Griffons, Chihuahua). For these breeds and many others, the health issues common in the breed challenge the ethics of continuing to breed them.

We will not begin to stem the tide of health issues in purebred dogs by doing more of what we already do. In response to the ruling by the Norwegian court that banned the breeding of Cavaliers and Bulldogs, the Norwegian Kennel Club said that it would continue to work with breeders to improve breed health through health requirements for breeding and other undefined measures. Similar statements supporting the Norwegian Kennel Club's position were forthcoming from the FCI, Australia, and other kennel clubs around the world. Breeders and kennel clubs are going to double down.

What is missing in these statements is the recognition that the underlying problem is not with the genetics of individual dogs, but rather it is a problem of genetics across the breed. For many decades, most purebred dog breeds have been part of a registration system that is strictly closed to the introduction of dogs from unregistered parents. The result is a genetically closed population, a group of animals trapped on a genetically isolated island. All individuals are necessarily related, having descended from the same original genetic founders, so all breeding will be to a relative. Each breed is a genetically closed population from which genes can be lost through selective breeding or just by chance, but the genes lost cannot be replaced because of the closed registry. The result is that the gene pool shrinks relentlessly, and the population becomes more and more inbred. Eventually, genetically closed populations, like those of purebred dogs, suffer an increasing burden of health problems, low fertility, and shortened lifespan until, eventually, they simply go extinct. This is the road most breeds are on, and the kennel clubs have said nothing in their recent statements about the breeding ban in Norway that suggests a plan to change this trajectory. In fact, doing more of the same, even harder and more carefully, will actually make things worse.

We have a complex problem to solve, one which the stakeholders - breeders and clubs - are simply not equipped to address. Each breed has its own unique set of issues, and our current strategy is to focus on one or a few of these at a time. However, it's not the individual problems that need to be addressed, but the underlying cause, which is common to all breeds. Purebred dogs are trapped in closed gene pools that force inbreeding. We will not solve the health problems in dogs until we abandon the closed stud book that prevents replacement of genes that are systematically lost every generation.

Opening the stud books would slow the pace of new problems, but restoring health to the many breeds that are badly damaged will require a systematic and well-planned strategy. Unfortunately, however, there is nowhere for breeders to go for help.

Here is where I think we need something for dog breeds that is comparable to the Mayo Clinic. Note that I specified "dog breeds" and not individual dogs. The health problems of dogs are a consequence of the genetic health and structure of the population of animals in the breed, and the solution must first be directed at the breed population, not the individual dogs. The approach must be integrated and specific for the circumstances of each breed. Coming up with the right plan will require a broad range of expertise.

The genetic rescue of the Norwegian Lundehund has taken this approach. Inbreeding of the Lundehund is 80%, the highest ever recorded in a dog (perhaps also in any mammal?!!), and the breed suffers from extremely low fertility and a gastrointestinal disorder than can be fatal. Before designing a breeding plan for genetic rescue, a team of scientists performed genetic analyses on the pedigree database and another team analyzed genotypes of both the Lundehund and breeds identified as potential candidates for cross breeding. Using demographic information, genetic modeling showed how different breeding strategies would affect the efficiency of a breeding program, e.g., how many animals would be required and how long would it take for gains in genetic diversity. Each animal used and produced is evaluated for health and relevant traits, and additional breedings are planned based on the parameters of the genetic model being followed. Done properly, with good scientific oversight, a genetic rescue program like this can demonstrate the effectiveness of the breeding strategy in two generations. For the Lundehund, the second generation backcross has produced healthy animals of good type that also carry new genetic diversity that can be integrated into the breed population.

To tackle the health issues of purebred dogs, we need to take an integrative approach. The diseases in individual dogs reflect choices made by breeders, constraints on breeding options imposed by the closed gene pool, division of gene pools based on geography, different preferences for type, the varied purposes for which the dogs are bred (show, working, pet), how breeders are choosing to manage genetic health issues, and many other things. The issues will vary by breed, as will the potential solutions. Tackling these problems will require the expertise of teams of scientists that can work out the critical problems and the range of practical options for addressing them. There will need to be tracking of animals and followup, periodic evaluation of progress, tending of pedigree databases and genotype data, and (perhaps most important of all) education of breeders so they can be full participants in the solutions for their breeds and have the knowledge to carry the breed forward with oversight when genetic restoration is successful.

A place like this does not exist, yet it is desperately needed now, to help breeders tackle health problems before more breeding bans are imposed on potentially dozens of breeds. Cornell University, my alma mater (PhD.), recently received a $30 million gift to launch the Cornell Margaret and Richard Riney Canine Health Center at the university's excellent veterinary school. Another gift of $12 million will establish the Duffield Institute of Animal Behavior at Cornell. These funds fortify what already was a strong concentration of resources in canine health and genetics at Cornell. But neither will address what is arguably the most pressing issue affecting the health of dogs: the burden of genetic disorders that result from traditional but outdated breeding practices and ineffective strategies for preventing disease. While disease research has improved our understanding of the illnesses suffered by dogs, it rarely has substantial impact on health because it doesn't alter the landscape of underlying issues that result in the production of genetic disease in the first place. To make a difference, we need an approach that focuses not just on the dogs, but also on the breeders. Breeders need access to education, to up-to-date data about the genetic status of their breed, and (especially) to expert guidance to replace the blizzard of opinions available on Facebook as a source of factual, relevant information.

Many breeds are now or will soon be at a crossroads - they must solve the serious health problems in the breed or face a ban on breeding. Addressing these problems will require creation of something similar to what I have described here, and it will require a significant initial investment, one that breeders will likely be unable to meet. Philanthropy can recognize the health problems of dogs because they are visible; it it harder to see the connection of the health problems to the underlying issues of inbreeding, closed gene pools, traditional but outdated breeding strategies, and misunderstandings about the proper use of DNA testing.

I don't see the problems facing dogs and their breeders being solved without a Mayo Clinic-like institution where a concentration of expertise can tease apart the layers of issues that must be addressed in order to restore dog breeds to health.

We know that genetic rescue is possible, but the infrastructure necessary to do it for more than a breed or two at a time simply doesn't exist. We know what we need to build if we can find the resources. The challenge now is to identify those that have a commitment to improving the health of dogs and can help pull together the resources to move this forward.

Cavaliers are in trouble

2/10/2022

By Carol Beuchat PhD

Since the action in Norway to ban breeding of Cavaliers because the heavy burden of health disorders violated their animal welfare act, there has been much heated discussion in these forums.

At the root of most health issues in dog breeds are the small size of the gene pool and high levels of inbreeding. Let me explain why these things are a problem.

The Cavalier King Charles Spaniel was founded on only a handful of dogs. I've seen numbers of 6 and 8; let's just call it a handful.

If the stud book is closed, then all the genes the breed will ever have come from those few dogs. Also, because the stud book is closed, dogs can only breed to related dogs. There are no "outcrosses" here; every dog is closely related to every other dog. It's a bit like trapping you and your immediate family on an island from which there is no escape. You can only breed with kin.

Over time, the animals in a closed population can ONLY become more closely related (genetically similar) to each other. Inbreeding can ONLY increase. Furthermore, gene variants are lost every generation through selective breeding and also just by chance. So the variation in the genes in those original 8 dogs is gradually lost over time. Eventually closed populations like this have such high levels of inbreeding that they are wrecked by health problems and infertility, and they simply go extinct.

In most societies, marrying your cousin is frowned upon. This is because your children would be inbred, at a level of 6.25%. For recessive mutations, that is also a risk of genetic disease at the same level of 6%. In most cultures, that disease risk is deemed too high, and these marriages can even be banned.

For half-sib pairings, the inbreeding produced in the offspring is higher, averaging 12%. Full-sib pairings produce offspring with inbreeding of 25%. For a recessive mutation in the genome, that is a 25% risk of producing an affected animal.

The problem with Cavaliers is that their level of inbreeding is extraordinarily high. We said that a full sibling cross resulted in inbreeding of 25%. Have a look at these two graphs.

I rounded up the data for two studies, one that included 10 dogs per breed based on US (mostly AKC registered) dogs Dreger et al (2016), and another that included data for 455 Cavaliers registered with the FCI, AKC, UKC, or the Kennel Club ( Bannasch et al., 2021).

For the Dreger et al. dataset (the red graph below), the inbreeding based on DNA for the Cavalier averaged 42.1% (black line), and for the Bannasch et al. data, inbreeding averaged 41.1%. For two unrelated datasets, of very different sizes, the level of inbreeding in the Cavaliers was essentially the same. This reflects the high level of inbreeding and genetic similarity among the dogs. It really doesn't matter how you sample the population, the estimate of average inbreeding doesn't vary much.

The black lines on the graphs are at the average level of inbreeding in Cavaliers in those two studies. (I have included links below to download the jpg file so you can blow it up big enough to read the breed lavels.) Remember, 25% inbreeding results from a full sibling cross from unrelated parents. The level of inbreeding in Cavaliers is way - WAY - higher than that. Most people would not do a breeding of two littermates, but the inbreeding data show that in fact most breedings are between dogs much more closely related (i.e., genetically similar) than littermates.

We do DNA testing to identify carriers of mutations so we can avoid the 25% risk of producing a puppy that is homozygous for the mutation. We know that every animal has many mutations lurking in its genome, and we can't test for the ones we don't know about. But the probability of producing a puppy homozygous for an unknown mutation is going to be the same as from a known one.

Cavaliers are all so closely related to each other that the average inbreeding produced in a puppy is 40% so the risk of homozogysity in a mutation is 40% as well.

Now, think about this.

You do your DNA testing to avoid producing a puppy affected by a known mutation, which you can prevent entirely by not mating two carriers.

But for all those unknown mutations in the genome, the risk of producing an affected puppy is the same as the average inbreeding, which is actually 40%, not 25%.

DNA testing allows us to test for carriers of mutations so that we can avoid this 25% risk of producing affected animals. But when all the dogs in the population are closely related, the average inbreeding of a litter is 40%, far above the 25% risk you're trying to avoid. You can see from this that health testing in Cavaliers is really not accomplishing anything except costing you money.

The problem with science is that it's true even when it's not what you would like to believe. The data for Cavaliers are clear. No amount of selective breeding is going to improve the health of this breed. You might temporarily reduce the incidence of some specific nasty mutation temporarily in a part of the population, but everybody is in the same genetic pot. Inbreeding will continue to go up over time, the small genetic differences between populations will disappear over time as genetic diversity declines, and eventually you will no longer be able to produce healthy animals. In fact, this is where Cavaliers appear to be now.

Cavaliers are in deep trouble. There are plenty of other breeds in similar shape, but what matters to those that love Cavaliers is whether it can be saved. We know that we can only restore health by restoring genetic diversity. We do know how to do with without losing breed type. Animal breeders have been doing this for hundreds of years to produce quality animals that can be nearly identical, with inbreeding levels in the single digits. It can just as easily be done for dogs as well, and Cavaliers are a perfect candidate. But not in a closed gene pool.

I have to say that what I have read on social media this week makes me worry that breeders will continue to argue about the arrangement of the deck chairs while the ship slowly slips under the waves. I hope I'm wrong.

REFERENCES

Dreger, DL et al, 2016. Whole-genome sequence, SNP chips and pedigree structure: building demographic profiles in domestic dog breeds to optimize genetic-trait mapping. Disease Models & Mechanisms 9(12): 1445-1460. https://doi.org/10.1242/dmm.027037

Bannasch E et al 2021. The effect of inbreeding, body size and morphology on health in dog breeds. Canine Medicine and Genetics 8:12. doi.org/10.1186/s40575-021-00111-4

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Hello breeders, this is Science

2/5/2022

By Carol Beuchat PhD

Purebred Dog Breeders:

RE: Improving the health of purebred dogs

In response to your queries regarding restoring dog breeds to health so as to meet the guidelines of the Animal Welfare Act, we make these recommendations.

ACTIONS

1) Open the stud book

2) Do not breed closely related dogs (a kinship cutoff of 0.10 will protect type and minimize risk)

We are happy to provide additional guidance at your request.

SCIENCE

The Norway breeding ban: what does the law say?

2/3/2022

By Carol Beuchat PhD

Norway's ban this week on breeding of Bulldogs and Cavalier King Charles Spaniels (see my previous post about this) has rocked the dog world, not just the dog fancy, but also the larger global community of dog lovers. Certainly among breeders, there is anger and despair, and loud calls to organize and "fight back" against what is seen as an attack on breeders of purebred dogs.

It's not helping that there is far more misinformation out there than facts. Rumors, assumptions, and opinions repeated a time or two on social media get shared more widely as they become more outrageous. People are posting all sorts of (mis)information that they got from ***somewhere***, to that point that a trickle of misinformation has grown to a torrent. The result is fear and confusion, and a growing sense that an entire community is passing through the stages of grief.

The best solution for this, of course, is facts. I am wading through the swamp myself, and I STILL have yet to find a copy of the court ruling in ENGLISH so we can actually know what it says. (Norwegian peeps, can somebody come up with this?) While we still lack clarity on many issues, I will share here a few things that should cut down a bit on the misinformation flying around. The facts should also confirm that purebred dogs are not doomed to extinction and there IS a way forward for for breeders.

First, the court ruling is based on Norway's Animal Welfare Act, which provides for the protection of the health and well-being of animals. Most countries have similar legislation.

In this case, the court cited violation of provision 25 of the Animal Welfare Act. You can see the entire document here on the governmental website for this legislation, but here are a few key excerpts.

Animal Welfare Act

Law | Date: 10/07/2009

Chapter 1

General requirements§

1. Intention
The intention of this Act is to promote good animal welfare and respect for animals.

§ 2. Scope
The Act applies to conditions which affect welfare of or respect for mammals, birds, reptiles, amphibians, fish, decapods, squid, octopi and honey bees. The Act applies equally to the development stages of the animals referred to in cases where the sensory apparatus is equivalent to the developmental level in living animals.

The Act applies, subject to the limitations allowed for by agreement with foreign nations or organisations, to Norwegian land territory, territorial waters, the Norwegian economic zone, aboard Norwegian ships and aircraft, on installations located on the Norwegian continental shelf, and to Svalbard, Jan Mayen and the dependencies.

The King may in regulations lay down specific requirements for Svalbard, Jan Mayen and the Norwegian dependencies, taking into regard local conditions.

§ 3. General requirement regarding the treatment of animals
Animals have an intrinsic value which is irrespective of the usable value they may have for man. Animals shall be treated well and be protected from danger of unnecessary stress and strains.

§ 4. Duty to help
Anybody who discovers an animal which is obviously sick, injured, or helpless, shall as far as possible help the animal. If it is impossible to provide adequate help, and the animal is domestic or a large wild mammal, the owner, or the police shall be alerted immediately.

If it is obvious that the animal will not survive or recover, the person who discovered the animal may kill it at once. However, animals from holdings or large wild mammals shall not be killed if it is possible to alert the owner, a veterinarian or the police within reasonable time.

Necessary expenses for action under this Section shall be covered by the state, but the expenses related to helping domestic animals may be recovered from the animal keeper or the owner.

The requirements in the first and second article apply equally for persons who injure animals, but a person responsible for injury to an animal may not claim reimbursement of expenses for action taken.

The King may issue more specific regulations regarding covering of expenses.

§ 5. Duty to alert
Anyone who has reason to believe that an animal is exposed to mistreatment or serious neglect regarding the environment, supervision and care, shall as soon as possible alert the Food Safety Authority or the police. The duty to alert applies subject to the limitations of other legislation.

Anyone who becomes aware that a large number of wild or stray animals are exposed to sickness, injury or other abnormal suffering shall as soon as possible inform the Food Safety Authority or the police.

§ 6. Competence and responsibility
The animal keeper shall ensure that animals are looked after by appropriately competent personnel. Others shall have the competence necessary to carry out the activity they are involved in.

Parents and carers with parental responsibility may not allow children less than 16 years of age to have independent responsibility for animals.

The animal keeper must not transfer animals to people if there is reason to believe that they cannot or will not treat the animal in an appropriate way.

The King may issue specific regulations regarding requirements for education, training and competence, including approval and authorisation of personnel.

A few salient points about this.

First, this is not a new law.

Also, it is not directed at dog breeders. In fact, it stipulates up front that it protects the welfare of everything with a backbone (e.g., mammals, birds, fishes, etc) as well as some invertebrate groups including octopi and honey bees. Yes, it protects both dogs and honey bees.

It explains that the legislation reflects our responsibility to respect the value of animals and to ensure their humane treatment, and it provides some basic guidelines for doing that.

The section relevant to the breeding of dogs is 25.

§ 25. Breeding

Breeding shall encourage characteristics which give robust animals which function well and have good health.

Reproduction, including through methods of gene technology, shall not be carried out in such a way that it:

changes genes in such a way that they influence the animals’ physical or mental functions in a negative way, or passes on such genes,
reduces the animals’ ability to practise natural behaviour, or
cause general ethical reactions.

Animals with a genetic constitution as cited in the second article shall not be used for subsequent breeding.

The King may issue specific regulations regarding breeding of animals in conflict with the principles in this Section.

That's the entirety of section 25 of the Animal Welfare Act cited by the court. It's only a few sentences, and it makes just a few stipulations. Most basically, it states that

"Breeding shall encourage characteristics which give robust animals which function well and have good health."

This seems like a perfectly reasonable requirement that most people could support. To avoid running afowl of the Norwegian law, the dogs we breed must be "robust, "function well", and "have good health".

Again, I haven't seen the court case so I don't know what specific information was presented about the health of these two breeds. But there is no shortage of data documenting the serious health problems in these breeds. Bulldogs are brachycephalic, with a shortened muzzle prevents temperature regulation and a throat anatomy that restricts breathing to the point that it can result in suffocation. The snoring that many breed lovers find endearing is the sound of the air fluttering as it moves over structures in the airways that block air flow. A snoring dog is having trouble breathing. Bulldogs are also at the top of the list of breeds that suffer from hip dysplasia, with 73.5% diagnosed as dysplastic in the OFA database, and essentially none are excellent. There are also issues with skin fold disease, spinal problems, and other disorders, but even the short list of the most serious problems would be enough bounce the breed off the list of breeds that could be considered "robust" and with "good health".

For Cavaliers, the problems are equally serious and well-documented. Mitral valve disease is terminal and afflicts almost all Cavaliers by the age of 10 years. The breed is notorious for the neurological disorders Chiari-like malformation and syringomyelia, which can result in a lifetime of severe pain and even paralysis.

Of course, not all dogs in either breed will suffer from a particular disorder. Disease prevalence is statistical. There will almost always be a few individuals out on the tail of the bell curve that are not affected. The few individuals that escape disease might live long, healthy lives, but these are not evidence of breed health because, of course, most of the afflicted animals in the body of the curve have died and are no longer around to be represented in the population.

I would imagine this is the sort of evidence the court considered in deciding whether these two breeds were in breach of the Norwegian Animal Welfare Act.

One last thing. There is lots of ink being spilled on issues that are not relevant. Most of the discussions I am seeing about this court ruling center on one of the issues I outline here (e.g., there is no problem in the breed because "I have a 12 year old Cavalier that has never been sick a day!"; or "This is an attack on purebred dog breeders by the animal rights wackos.", except that it's not.)

Breeders can't have an effective discussion about how they can bring their breeds into compliance with the law unless they focus on the problem at hand. This is not about puppy mills or the extinction of show dogs. The problem is health of the dogs you breed. Focus like a laser on that.

Here's a way to think about this. If there are lots of serious accidents at a particular intersection, the traffic people might decide to put up signs for a 4-way stop. This will drastically cut down on the number of accidents, making the intersection much safer for all. But, the stop signs might result in a line of cars backing up to get through the intersection, making people late for work, or even encouraging people to speed or drive recklessly to make up for lost time. Are these reasons to remove the stop signs? No. You have health and welfare problems to solve. Ignore all the other potential knock-on issues that are not your responsibility to solve, and leave those to the powers that can do something about them. Your single responsibility is resolving the issues that compromise the health of your breed. Don't waste time and energy arguing among yourselves about how to solve what are clearly complicated problems. Ask scientists and veterinarians for help.

We all want healthy dogs. You can do this.

Norway bans the breeding of Bulldogs and Cavaliers. Now what?

2/1/2022

By Carol Beuchat PhD

Unless you have been underwater for the last 24 hours, you will have heard about this. I'm not a lawyer, and I haven't yet seen a copy of the ruling in English so I don't know the exact details. But I can provide some basic background that I hope will result in more productive discussion among breeders.

In the 1980s, laws were passed in the United States designed to protect the welfare of animals. They apply to ALL animals. As a scientist that works with animals, I have to abide by these laws as well. Any study I wish to do that involves animals *** IN ANY WAY *** must be reviewed by a university committee that includes experts in the field, veterinarians, and people who evaluate issues of ethics and animal welfare. If I want to go bird watching for fun this weekend, I grab my binoculars and go. If I want to study the courtship behavior of pelicans, I must write a proposal that provides the background and justification for the study, and details about any way in which it will affect the animals. There must be specifics if the protocol will produce any discomfort or pain to the animal or alter its normal behavior. For lab studies, it must address housing (cage details, room temp, airflow, feeding and care, etc). For field studies, it must cover things like individual interactions, territoriality, nesting, feeding, and how far away observers will be would all be under scrutiny.

Every research protocol must be approved by this committee before any study can go forward. In the Methods section of the published papers you read, you will see a statement confirming that the procedures involving animals were reviewed by an institutional animal care committee. If you want to collect a DNA sample using a cheek swab, the procedure must be described and approved by this committee.

This entire process proceeds under the stipulations of the animal welfare legislation. If there are violations, the research can be terminated and grant money rescinded. In fact, serious infractions can result in ALL the federal research money at a university – for EVERYBODY doing research - being frozen until welfare issues are addressed. If the university does not comply with the regulations, everybody’s research programs are shut down.

These laws have been on the books in the US for decades. Other countries have similar laws. Now in Norway, a case has gone to court that argued that welfare laws were being violated in the breeding of two breeds, Bulldogs and Cavalier KC Spaniels, because of their well-documented health issues. The sides made their cases, and this week the court agreed that the breeding of these two breeds was in violation of laws that protect the welfare of animals.

This is not an attack on breeders. It simply applies existing law to a group of animals, purebred dogs, that have been flying under the radar of animal welfare legislation. If there were no welfare issues for these two breeds - i.e., that the dogs being produced can be expected to be healthy and not suffer from serious or systematic health issues that could cause pain and suffering - there would have been a different outcome.

This is not the beginning of an indiscriminate attack on all breeds. It is, however, a test case based on two breeds that makes it clear that the existing welfare laws in Norway apply to dogs just as they do to other animals. Everybody must abide by these laws because they protect the welfare of animals.

Breeders are screaming that this ruling is unfair, that they must "fight", that this is "anti-breeder", and violating the "rights" of breeders. These things are not true. The laws apply to all animals. Breeders do not have any special “rights”; they must abide by the welfare laws too. For this reason, appeals will be lost if the issues about welfare are not resolved.

Pushing back against these laws will put you in the awkward position of having to argue that you should be able to disregard welfare issues that are serious enough to run afowl of the laws that apply to everybody. If this is your plan, you should start working on your defense now.

The solution to this is simple. Go down the list of breed-specific health issues of dogs and get started solving those problems. Some of the problems are written into breed standards - muzzles too short for effective thermoregulation, skin folds that promote infection, short backs that result in deformed vertebrae and herniated disks, etc. Others are unrelated to conformation, but reflect exceptional risks for health issues, often for a specific breed - death from DCM, various cancers, seizures, allergies, hip dysplasia, degenerative neurological diseases, and others.

Breeders will argue that they have been prioritizing health and trying to solve these issues, but in most cases they have been making little progress. There are lots of reasons for this, but the scientists will tell you that there is one, single, significant issue at the root of most of these problems - the closed stud book.

Here's the bottom line. You cannot solve health issues if you lack the genetic diversity in the breed to select for genes that would restore health. You can't. It's as simple as that.

Science knows how to solve these problems.

There is now a published study documenting a breeding program for Norwegian Lundehunds that is achieving success in solving serious health issues of this breed. They didn't have a lot to work with - a small population of dogs globally with an average inbreeding coefficient of 80% (!!!). But under the direction of an international team of scientists, breeders have restored genetic diversity through a cross-breeding program while preserving the traits that make this breed iconic and unique (Melis et al 2022).

Melis et al 2022 Genetic Rescue of the highly inbred Norwegian Lundehund. Genes 13: 163.

If we can accomplish the restoration of a breed like the Lundehund to health in a few generations, it should be possible with any breed. You just have to do it.

The laws protecting the welfare of animals are already on the books in countries around the world, including the US. If you are unaware of them, it is simply because they have not been enforced. But they apply to dogs just as they do to any other animal. Probably sooner than later, they will be enforced for dog breeding in the US as well, and no amount of protesting or lobbying is going to carve out an exception for breeders that will allow them to simply carry on without change.

Stop worrying about puppy mills, the unethical and irresponsible breeders, and all the other groups that are usually blamed for the health problems of purebred dogs. Those folks will eventually need to abide by the law too.

Focus instead on the changes that need to be made in your breed so they meet the standards of health and welfare under the law. These standards are not unreasonable.

Can breeders do this? Of course they can. In fact, there is nobody better suited. Breeders have the experience in husbandry, the breed knowledge, and a commitment to prioritizing the health and welfare of dogs. Enlist the support and guidance of scientists and other experts so you can develop breeding strategies to solve problems in the most efficient, practical way. If you are going to put in the effort to do this, get expert help so it actually gets done, or that you at least minimize your risk of failure.

We have passed the tipping point. It’s clear the direction things will take from here. Dog breeders, like everybody else, are obligated by law to protect the welfare of dogs, and we should embrace this responsibility. It’s the right thing to do.

REFERENCES

Melis, C, C Pertoldi, WB Ludington, C Beuchat, G Qvigstad, & AV Stronen. 2022. Genetic rescue of the highly inbred Norwegian Lundehund. Genes 13: 163. https://doi.org/10.3390/ genes13010163

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