Snowy, the double merle breeder sheltie, blind - deaf - mute - club footed. Everything you want out of a brood bitch.
The blog got a nice shout out in the comments of a recent post at Pharyngula: “Written by a border collie owner who is interested in and actually understands a fair amount of genetics” (love when people appreciate the blog) but the rest of the comment is an interesting introduction to a video of a double merle sheltie with hearing and vision problems and possibly a seizure disorder.
Anj says: 5 November 2011 at 7:56 pm
Cats doing something truly insane?
Might be a seizure disorder. “Fly biting” (snapping at apparently nothing) or any momentary action that seems completely unconnected to any environmental stimulus may well be seizures.
I am interested in genetic disorders of dogs and cats mostly because I wonder why we breed dysfunction into animals we supposedly love and care for. Sorry to say, some of those pet quirks that people think are unique or funny are may be signs of congenital disorders.
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The dog in the video does appear to snap at invisible flies in the air and has a general loss of coordination and tongue control. So too, as Anj predicted, these twitches are seen as cute by the owner. The comments on the video make it clear that the owner isn’t reveling in this dysfunction as much as sharing their experience with a dog they rescued.
I think it’s cruel to breed double merles, they can become deaf and blind. Is it forth of the white colour? 🙁
Sxcs00 3 years ago 3I agree, It is a horrible practice. We got Snowy from a rescue, but before we got her she was used as a breeding dog, even with all her issues.
keenergc 3 years agoyour dogs are beautiful. i too have a sheltie (sable & white) whom i love to death. how did snowy become both deaf and mute? ive never seen a white sheltie before, let alone one who is deaf and mute
yorktown99 4 years agoShe is a double merle, a genetic defect that can happen from bad breeding – when merles are bred together. The deafness is common with that. as for being mute, she was born with excess cartiledge around her trachea that won’t allow her voice box to work. She also has a club foot and limited vision, but she is a happy little thing despite all!
keenergc 4 years ago 2
Unbelievably, “Snowy” wasn’t just a placement of an unfortunate pup, she was a breeder who was dumped after. That suggests to me the worst kind of breeder, who would intentionally create a double merle dog just to create merle puppies. How jaded and monstrous must you be to look at this dog as a cash cow? How callous to you have to be to think, “this is good for the breed, for the dogs, for their new families!” ?
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I came across a Sheltie breeder who defends breeding merle to merle: http://www.kennelcity.com/cdgrdub.html
Not all breeds have the same percentage of bad problems with double merles, but I think what she wrote is essentially irresponsible.
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I notice that she doesn’t mention how many of those 80 double merles she’s produced so far had defects.
Well, to be fair, the point she is making isn’t that double merle shelties have no blindness or deafness problems, the point is that “colored patches on the heads of double merles are irrelevant to their blindness and deafness.” Which, as far as I know, is exactly right.
That does not excuse the line slightly later, “I was so hoping for a good double merle from this litter.” I will posit that it is possible that the best possible breeding for a breeder’s goals may be a merle x merle breeding. But the only reason to /want to keep/ a double merle from that litter is to get all merle puppies in the next generation.
I don’t think merle should be selected away from, because the last thing most breeds need is heavy handed culling of the breeding population, but I would not be sad if one day I woke up and every merle dog had turned solid in his sleep. And for godssake, keep it out of breeds where it isn’t already! I’m looking at YOU, Chis, Poms, and Cockers.
I don’t know that the “color patches on the head” observation is even relevant any more for these reasons:
(1) We have very accurate and precise tests to measure hearing loss and vision loss, so we don’t need the “tea leaves” sort of measure.
(2) For the most part breeders can’t control the amount of color on the head, so it’s not exactly something that can be a tool to breed more double merles that happen to have color on the head where it would prevent eye and ear issues.
So why are some breeders so passionate about this issue?
(3) Perhaps they want as little color as possible and to the extent that they can control color on the head they don’t want to be held accountable for causing greater deafness and blindness.
(4) Is this a legacy from the desire to recreate a white collie? (the wrong way… instead of going for lighter shades of eeRed they go for knock-out color genetics like merle, piebald, harlequin, etc.)?
I actually suspect that there WOULD be a correlation between amount of color anywhere on the dog (including the head) and deafness and blindness. And I wouldn’t be surprised if the head color was actually even more highly correlated. The studies that have been done seem to confirm that the more bleaching genes present (merle, piebald, harlequin), the greater the chance of deafness and blindness and also the less visible color on the animal. So the two would pretty much have to be correlated on the base gene level. I also suspect that they’d be correlated on the patterning level.
Not that it really matters, I don’t see much value in the differentiation. Perhaps this is more important in a breed like Collies where I guess some fads have people trying to breed mostly white bodied dogs with some color on the head.
She only came to this realization by breeding lots of merles to merles, which is a big no-no.
That’s the irresponsible part.
People have tried to make breeds that consist of only merles. Most notably the harlequin pinscher, which was both merle and harlequin in its genotype– just like the harlequin Great Dane. Harlequin is lethal when inherited homozygously– the pups aren’t born. And if you have a bunch of double merles in a litter, you’re going to have problems.
The harlequin pinscher is now an extinct breed, though some people have recreated a merle miniature pinscher through crossing with merle rat terriers and dachshunds, but that old harlequin pinscher breed is extinct.
It was just unsustainable.
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Until I see a study which compares breeds using a sound method (like looking at whole litters, not just tested adults), I don’t think there’s much value in assuming that some breeds are magically protected from the effects of double merle.
Every breed with merle produces these monster dogs, so if there is a difference, it’s a matter of degree, and really, is there someone out there who wants to make a moral argument based upon degree?
Catahoulas seem to come close. http://www.donabney.com/issue_merle.php
I’m not sure, but Dachshunds might as well. The problems of double merle do seem to be more prevalent in dogs that are also white spotted.
I’ve seen that page before and it’s fascinating. Note that none of those dogs appear to have any of the other white-factor genes: no Irish markings, no piebald, no harlequin). I’ll also note that the theory on that site is that one of the copies of the merle is actually defunct or highly limited. That is no consolation for anyone who wants that color expression. If the dog has one copy and it’s a short segmented merle, the dog doesn’t really display the merle phenotype. At that point we may as well rename the gene to something else. I’m sure that if this were studied, if we have two full copies of the merle gene, we not only see the results we see the disease as well.
You can get problematic double merles in Catahoulas. As a breed, they may be less likely to get the problems.
But the risk of producing a problematic merle is very high when you breed merle to merle.
The other problem I have with merle is that you can have cryptic merles,and you don’t know when you’re breeding merle to merle.
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The risk of producing even one dog with these sorts of disabilities is too high to merit merle to merle breeding.