Saturday, 16 November 2013

Breeding Difficulties part two - breed predipositions

As a vet student, and as a new vet, I hadn't really thought much about dog breeding. Dog breeds, to me, meant a list of predisposed diseases that I had memorised by rote as part of my training - something a little like this:

            West Highland White Terriers: Atopy, Lens Luxation
            King Charles Spaniels: Mitral valve insufficiency, syringomyelia
            Boxers: Aortic stenois, neoplasia, idopathic syncope          
            German Shepherds: Anal furunculosis, atopy, pannus, dilated cardiomyopathy, hip dysplasia, chronic degenerative radiculomyopathy[1]

 ... and so on. Questions on this would pop up all the time in exams, so you needed to know this stuff[2], but I never really considered what this list meant. It was just something else to learn: parathyroid hormone is responsible for the regulation of calcium levels within the body, the average pH of a pigeon's rectum is 6.3, and greyhounds are predisposed to develop osteosarcomas.

 Our family pet when I had been growing up was a cocker spaniel, Silky[3]. I loved her dearly, as you would expect. It was harder for my dad to; she was extremely protective of her bed, and would growl and snap at him whenever he approached. She did the same to all of us if she ever wriggled under the bed, and she once bit me quite badly on the finger when I tried to extract her. At university, I learned that this was in inbred trait of spaniels - rage, it's called[4]. So, it turns out, was the heart disease that claimed her life. Still, these things never really connected; by the time I qualified, Silky had been dead a long time, and my parents had another spaniel at home[5]. We knew the breed, you see. We liked them.

In practice, this knowledge of breed diseases was very helpful. Young labrador, unsteady on its back legs? Definitely worth x-raying the hips for dysplasia. Westie with breathing difficulties and crackling noises on auscultation of the chest? Need to investigate the possibility of pulmonary fibrosis. Very helpful. Essential, in fact.

In those first few months, I was living from one consultation to the next, terrified that I was just one slip of the needle away from making some colossal mistake. Eventually, though, as the terror of being a new graduate slowly settled into a dull, lurking fear, and I started to see consultations that weren't wholly new to me, I began to notice just how much of my time was being taken up treating diseases that were on that list. Even for someone as slow on the uptake as me, when faced with my third westie in the same week with severely inflamed and infected skin due to its chronic allergic skin disease, I started to ask myself questions about whether there might be a better way of dealing with this stuff.

Suffering. It's a word that's followed me through my life, and through my career. As vets, we use it a lot. We are, we like to think, its enemy. Our whole raison d'etre, our vocation, is to reduce it whenever and wherever we can. It's the reason we can euthanase five animals in a day, and still get to sleep at night  - we didn't want them to suffer any more.

Working in general practice, it finally started to click with me - this rottweiler with entropion wasn't helping me out by presenting me with a disease I knew it was predisposed to. It was in pain, because its eyelashes were pressing onto its cornea. This springer spaniel with purulent otitis externa was yelping when I examined it because it hurt. That great dane that I put to sleep last week due to dilated cardiomyopathy wasn't just another tick box on my mental list of breed diseases. It was dead, because it's heart gave out. Because it was a great dane.

That's when I started to wonder about that list. Breed predisposition. It meant that, genetically, these breeds paid a price for their long ears, or their curly tails, or their short, cute, forelimbs. It meant that they were more likely to get certain diseases - and, from my experience in practice, I was realising that this didn't just mean a bit more likely. Something like fifty percent of westies have atopy. The same proportion of bulldogs can't give birth without a caesarian. I was coming to understand that the price a dog pays for being a certain breed is that it suffers.
I finally started to think very seriously about dog breeds, and just what we were doing to man's best friend. 

The bulldog caesarian I described in my last post is, I don't deny, an extreme example - but the point of this post is to demonstrate that no breed is immune. The pedigree dogs we have now are not the same creatures that existed fifty years ago; through more and more inbreeding, they've become caricatures of themselves.

Next time, I'm going to talk about breeders, puppy farms, rescue centres, and what we can do to try to fix this problem, and therefore stop me blogging about it - something I think that we can all agree would be a good thing ;).

[1] This is not, by any means an exhaustive list for any of these breeds.
[2] And why, due to a particulcarly stressful 'steeplechase' exam in my fourth year, I will remember to my deathbed that Belgian Shepherds are predsiposed to gastric adenocarcinomas.
[3] This is what happens when you allow your children to come up with names for your family pets, of course. We all liked the name, anyway. Don't judge us.
[4] Which puts me in mind of the excellent not-zombie film, 28 Days Later. Definitely worth seeing! But I digress - I suppose I'm allowed to in a footnote, now I think about it...
[5] Bilbo, if you must know. Hey, I like The Hobbit, okay? (The book, obviously).


  1. Just read part 1 and 2 great blogs, very interesting reading about the breeds of dog today, look forward to reading more. Thanks nick.


  2. Thanks, Jeanette. I'm planning one last post about the subject, hopefully in a more constructive 'what can we do' frame of mind :)

    1. It must be heart breaking for you nick to see the animals in such distress and discomfort, maybe putting leaflets in vets surgeries maybe a idea...not sure what ideas you might have but it's a little idea, I know it's cost for you...or maybe a web page about it, I look forward to your next blog thanks for your reply.


  3. I'm enjoying this series too. I actually don't see a lot of purebred dogs in my current practice --- maybe military families are more likely to adopt mixed breeds for some reason? That means I haven't had a lot of personal experience with some of these breed predispositions, but I try to keep it in mind whenever I'm working up a list of differentials.

  4. Love it, especially the part about doing something practical to try and make a difference. I'm always game for helping bring good ideas to life.

    As a side note, there was a recent article looking at mixed breed dogs vs. purebreds and except for a a few, there were not more congenital diseases in purebreds than in the mixed dogs. Granted, not sure how many of the "mixes" were labradoodles and the like without much genetic variation, but it was interesting to think that it doesn't just apply to our purebreds either. Hybrid vigor may not be all it's cracked up to be.

  5. Any chance I could get a link to that article? Interesting. The problem with 'mixed' breeds like labradoodles and cockerpoos, of course, that they're now being bred with each other, rather than produced from labs crossed with poodles, etc, further dropping their variation.
    However... bear in mind that almost none of the diseases mentioned above are congenital - you're not born with atopy, or hip dysplasia, or mitral valve disease. You're just born with the propensity to develop it over time, so I'm not sure the study is looking at the sort of things I'm thinking of.
    P.s. apologies for the multiple revisions to this comment - that's what you get when you try and reply to your own blog on an iPhone ;)

  6. Okey doke, I've dug out the study, from UC Davies, it's actually about genetic disorders, not congenital. Here's the details... the headline suggests that mixed breed dogs can be more prone to certain genetic disorders (like cruciate disease).

    I'd rather people read the figures themselves and came to their own conclusions, but here's a quick summary. 24 easily identifiable genetic disorders were checked for in 90,000 dogs. Of those disorders, 13 were no more or less likely in purebred dogs. 10 -were- more likely to occur in purebreeds, and 1 was more likely to occur in mixed breeds.

    I hate putting spin on things, wihch is why I have shown my working, but that does rather suggest that purebred dogs are more prone to ten times more genetic disorders than mixed breed dogs...

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