Friday, December 26, 2008

Flawed Paws

Dr. Paul Mcgreevey writes in New Scientist:


In the wake of the documentary [Pedigree Dogs Exposed], leading animal welfare charities such as the Dogs Trust and the RSPCA have spoken out against pedigree dog breeding, and withdrawn their support for Crufts, the UK Kennel Club's flagship event. It is time for a new approach to dog breeding: that is based on a comprehensive understanding of their biology; that values health, longevity and suitable temperament; and that ensures we get the best out of companion dogs by helping them to help us.

Many veterinary geneticists saw the crisis that now faces the Kennel Club looming many years ago. The closed studbook system used by pedigree breeders inevitably involves inbreeding that increases the risk of inherited disorders caused by recessive genes. Such disorders are now recognised in all established breeds of dogs and cats, as well as horses, farm animals and a growing number of captive exotic species. But the problem is worst in dogs, which have been intensively bred within the closed studbook system since Victorian times. Many dogs now have inherited disorders that cause them to suffer so much that it is unkind to keep them alive.

Worse, pedigree dog breeders compete to produce animals that conform to written standards, which may include morphological and behavioural traits that compromise quality of life. These traits were incorporated into the first breed standards when dogs left the working arena and entered the world of dog shows in the late 1800s, and many of them may have been valued by early dog domesticators because they served a particular purpose. Unfortunately breed standards now tend to prioritise appearance over functionality.

For example, the breed standard for Weimaraners demands that the chest is "well developed, deep" while the abdomen is "firmly held" and the flank is "moderately tucked-up". These requirements may help to make Weimaraners appear athletic but veterinarians know that breeds with deep chests are at risk of gastric dilation and torsion, an extraordinarily painful, life-threatening condition in which the stomach bloats with gas and can become twisted. Or take the Pug, which according to its breed standard should have eyes that are "very large, globular in shape". Breeders oblige the judges and select for this feature, leaving Pugs with eyes that bulge so badly their lids scarcely meet well enough to wipe the eyeball clean. The poor dogs undergo a lifetime of chronic conjunctivitis that eventually scars over the cornea and blinds them.

The emphasis in dog breeding needs to shift. To minimise rates of inherited disease, closed studbooks may need to be abandoned.There are also calls for each breeding population of dogs to be placed under surveillance, so that new disorders can be tracked as they emerge.

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9 comments:

Mike Spies said...

I think, to be fair, the culprit is NOT closed breeds - that is, breeding within registered populations of a breed. The problem is the breeders and breed standards.

It is common practice in the AF (FDSB) to breed based on performance. In the FDSB here are NO written breed standards to tilt the table away from performance.

In this scenario genetic faults may still appear - but they are minimized by breeders' efforts to produce a better performing dog. And the use of selective breeding (pedigree breeding, if you like) is a major tool to accomplish this. So 'pedigree breeding' is a blade that cuts both ways.

My Blog is - Living with Birdogs - www.wenaha.blogspot.com

Mike Spies (mike@autohomeus.com)

Gina Spadafori said...

Well ... yes and no.

Example often mentioned here: The flat-coated retriever, a breed to which I happen to be thoroughly committed and with which I happen to be utterly besotted.

The flat-coated retriever's standards emphasize a dog that's "moderate" -- size, coat, etc. -- in accordance with what would be useful for a working retriever.

The breed hasn't split into "field," "show," "pet" and "agility" lines, and most flatcoats could do it all if their owners were so inclined. Most flatcoat show champions could in fact hunt well enough to be a companion hunter, if not a top competitive field-trial dog.

There's nothing wrong with the "blueprint" for a good flatocat as described by the breed standard. And most flatcoats are very athletic and healthy, with low rates of hip dysplasia, bloat, allergies, etc., etc. ...

.... except for one major thing: An extraodinary and tragically high number of these wonderful dogs die of cancer, typically between the ages of 8 and 10, although some much younger.

It's caused by a genetic bottleneck and furthered by closed registrations (and minds). Planned outcrosses would fix it and leave us with a flatcoated retriever that's everything we love about the breed -- but without the high rates of early death to cancer.

I think the day is coming when you'll see not only changes to the breed standards to fix language that calls for conformation that's not in the best interests of a healthy dog, but also changes to the way we consider what a "breed" is so we can outcross to get some deeper gene pools.

Personally, I can't wait to see that day, for all dogs.

PBurns said...

If you are ACTUALLY breeding for pure peformance, then you do not care if a dog is registered, or if its progeny are registerable.

In fact, you do not even care about the BREED of the dog in question. You will sort all that out after the pups are born, perhaps calling the smooth coats "pointers" and the feathery coats "setters," and the smaller setters "spaniels." Either way, the dog will do the job, and the type will always play second fiddle to the work, and the color of the dog (and the shape of its head) will be ignored entirely.

This is, in fact, how bird dogs were created, long before the creation of the Kennel Club or American Field. As a result, these early dogs had a high degree of heterogeneity, and a pretty low incidence of any one health problem.

Today we generally do no breed that way, and the dogs suffer as a result -- look at the 20-35 percent cancer rates in setters and pointers for example. This is not a mark of success!

Today, when we talk about "selective breeding," the first selection is not for work, but for registry. In short, the work is almost never first; it is always second at best (and actually often third or fourth in practice, wiht coat color and head shape often getting the second or third slots).

That said, let me say that long-term breeding of healthy dogs in a closed registry IS possible if the dog pool is quite large and diverse at the beginning, and if attention is paid to keeping a low coeffcient of inbreeding going forward.

If the initial pool is small, however, and there is a lot of use of favorable sires (no matter why they are favored), you are on the fast and slippery slope to canine disaster due to rising Coefficients of Inbreeding (COI) leading to predictable disease and defect.

And this is true no matter how the dogs are selected.

In the case of bird dogs, for example, breeders may correctly weed out dogs with juvenile cataracts, but keep in the breeding pool those dogs with later-onset problems such as cancer which will hit at age six or seven. If the breeding pool is small and narrowing (as it mostly is with dogs bred in closed registries), the result will be a rising level of canine cancer.

The cost of inbreeding and/or narrow gene pools has been known since the dawn of time and is easy to track. Lets look at what happens when humans marry first cousins, for example. As it notes at >> http://www.independent.co.uk/life-style/health-and-wellbeing/health-news/inbreeding-causing-rise-in-birth-defects-780562.html , in the UK, Pakistani parents produce just 3.4 per cent of the babies, but these babies account for 30 per cent of children born with genetic illnesses. What's going on? Simple: Pakistanis in the UK are much more likely to marry first cousins, and the results are predictable and quantifiable. The Birmingham Primary Care Trust has estimated that one in 10 children born to first-cousin marriages either die in infancy or suffer serious disability as a result of recessive genetic disorders.

The same thing happens for dogs, of course.

As the late John Armstrong notes at >> http://www.canine-genetics.com/pgbreed.htm :
"The COI has predictive value. I can tell you that a [dog] inbred to only 5% will, on average, live about 3 years longer than one bred to 35%, and I can tell you that a 10% increase will likely reduce litter size by about 7%."

Bottom line: if you are breeding dogs in a closed registry system, you are NOT putting work above everything else, and you have to be hyper-aware of the coefficient of inbreeding if you want to keep the dogs healthy over time. If you are ignoring COI and simply breeding "best worker to best worker," while letting COI rise, you are on the quick and slippery slope to long-term problems. If you are keeping at eye on COI, however, and if the pool of dogs is truly large and diverse, you are probably going to be much better off.

Patrick

retrieverman said...

@Gina Spadafori: I can tell you exactly what breed to use for that outcross, and this breed would also benefit greatly from that outcross. (Hint: it's the "forbidden" color of the flat-coat that became a separate breed for some reason).

I don't even think trialed dogs are all that bred for performance, except for trials. A lot of field-bred Labradors are too wild to be used in a normal hunting situation.

Maybe competition isn't what we need to produce good dogs. What we need is to breed dogs that do that function well instead of who has the most game terrier or who has the retriever that can be handled from 200 yards (using whistles- an idea stolen from sheepdog trials). I can see working trials as being as much a problem as conformation breeding.

The problem with us dog people is we like to brag and argue, and this creates a situation of discord that makes competition very likely.

I just want a dog that has the right behavior and working conformation. I really don't need a dog that beats another person's dog in some esoteric competition of any sort.

Seahorse said...

I've been dogless since my last Jacks died a few years ago, and had always felt I knew a fair bit about dogs but never professed to be an "expert". Since reading this blog for a while now, reading all the comments it generates and talking to some breeders as I ponder getting dogs again, I have to thank each contributor for my latest education. I was watching "Dogs 101" last night and could just feel the clunkers, mythologies and nonsense coming across the airwaves. If it helps just one person get sturdy, healthy new dogs, I hope you feel your time was worth putting in. Thanks.

Seahorse

PBurns said...

Thanks Seahorse -- Kind words, and indeed my motivation.

Patrick

Mike Spies said...

A dog (like any living thing) could be viewed as a funnel for the genetics of all its ancestors. If we want to breed better dogs, we need to understand the ancestry of the dogs we are breeding - and understand the strengths and weaknesses of these ancestors in some depth. We also need to understand how these genetics are expressed, and whether one or the other of the parents are 'prepotent'.

IMO, the strategy of breeding a sound dog to a sound dog is a simplistic form of selective breeding. But without an understanding of ancestry it is a crap shot and lacks consistency of off-spring.

Elimination of faults within a breed (or race) of dogs is not done in a generation, but in a consistent, planned program of breeding over many generations, so that the expression of detrimental genes can be minimized through selection and culling (removing unfit candidates from the breeding gene pool). This can be done if the breeder(s) have access to a large enough gene pool and breed for soundness and performance. It is not for the weak of heart or uncommitted.

This is one reason why I have little use for 'specialty' breeds - the ones that people seem to seek out because they are rare or unusual. Not a healthy situation.

As for rates of cancer in setters and pointers - there is a definite split between the bench bred and field bred dogs in these breeds. I have seen both setters and pointers that were bench bred and seen them 'work' in the field. Poor in conformation and ability does not begin to describe them. The field and bench gene pools have been more or less separate for some time - over 75 years perhaps. To lump them both together to calculate the incidence of cancer in the 'breed' is a deception that distorts what is actually going on.

Coefficient of Inbreeding (COI) is a tool that breeders use, but they largely disagree on what represents a 'high' COI. The strategy that has worked well for breeders of performance dogs over time is to line breed to fix positive characteristics and eliminate negative ones (usually - but not always - producing females with a COI of about 15 or so), then to out-cross to an exceptional dog from a similarly focused, but largely unrelated, line of dogs. This strategy has proven successful in producing superior performing dogs that have less negative genetic baggage.

Among the bird dog community, field trials provide an opportunity to judge the performance side of the breeding equation under informed and impartial judgement. This has the larger effect of providing an index of performance across the breeds that participate - and results (usually) in better breeding decisions.

Thanks for creating the opportunity to discuss this in a sensible forum.

M

Anonymous said...

Hi Patrick,

I was in a bookshop yesterday and found a book that I think would interest you. It's called Blood Matters by Masha Gessen. It's about genetic disorders in human rather than dog communities. Looking at the issue as it affects humans is an interesting perspective.

Gessen writes about particular genetic diseases which are prevalent amongst Ashkenazi Jews and also ones prevalent amongst the Amish and Mennonites. Coincidentally I have forebears that come from both these communities so I found it particularly interesting. My forebears chose to "outcross" rather than stick within their own communities!

Gessen doesn't seem to fully understand the history of the Swiss Anabaptists who are the ancestors of most of the Amish and Mennonite groups she writes about but one thing that interested me was that it was the Anabaptists' propensity for splitting into subgroups which then didn't intermarry that's probably been the main source of the genetic problems found in their communities.

Amanda

PBurns said...

Thanks Amanda! I have not seen the book, but coincidently dogs are often used for human disease and defect research because the Kennel Club has unintentionally but quite purposefully bred dogs for defect and disease and kept pedigree records through which geneticists are able to trace the pathology. There is even a web site devoted to all this >> http://www.eurolupa.org/public.html

Patrick