Natural History

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13 Responses

1. on March 19, 2011 at 10:26 am Stephanie Briggs

   That poor dog! :( On the other hand, as a disabled woman, I’m rooting for him anyways. Is this a painful condition?

   I think we are a lot kinder to animals than we are to our fellow humans when it comes to illnesses that cause intractable pain and suffering. Most of us wouldn’t think twice about putting a beloved pet to sleep if she was in constant pain, but we cringe at the same thing when it comes to humans.

   
   
   • on March 19, 2011 at 1:19 pm Dave

     @Briggs Eh…

     I find people who are unable to cope with putting down their pets are the same people who cannot deal with the idea o having a relative pass away.

     @Retrieverman DAMBUSTER FOR DENIALIST BREEDERS!

     
     
   • on March 19, 2011 at 2:00 pm Christopher@BorderWars

     Stephanie,

     I agree that we are better with our animals. Which is surprising because of our inability to communicate with them the nature of the problem. We can’t ask them to weight the disease versus a good death.

     In researching my post, I came across this thread:

     http://handicappedpet.net/helppets/viewtopic.php?f=29&t=13347

     I’m actually inclined to side with the Vet on this one. I think they needlessly extended this animal’s suffering and perhaps made it worse with surgery.

     The vet could have EASILY just cashed their check.

     
     
     • on March 19, 2011 at 4:02 pm Jess

       In my Wees litter, there was a male pup that had a persistent right aortic arch, with subsequent megaesophagus. When he was four weeks old, he suddenly presented with severe pneumonia, and we had a barium x-ray done. There is a surgery for the condition, but it’s very, very expensive, has to be done by a specialist, will not fix the megaesophagus (that damage is done), and must be done on a healthy pup, not one sick with pneumonia. I euthanized the pup. Frankly, if my vet had suggested going to a specialist for a risky surgery on a very sick pup, I’d had let him have it.

       I have seen people jump through exhausting, expensive, and ultimately fruitless hoops to keep a defective pup alive. There is a reason that dogs have litters. If that sounds heartless, so be it.

       
       
       • on March 19, 2011 at 5:39 pm Pai

         I don’t think it is. Overhumanizing dogs does more harm than good, in my opinion. I feel the same when I see some of the twisted dogs at Ugly Dog Contests (like this years’ winner) — it would’ve been kinder to put them down rather than ‘rescue’ them, imo.

         
         
2. on March 19, 2011 at 5:12 pm tracey

   my sheltie merlin is a double merle, deaf dog with microopthalmia. i rescued him when he was 14 mths old so i know nothing of his breeding, it does upset me greatly to think someone may have bred two merle dogs to create a white merle. he is a lovely fun boy who is as fit as can be and so far thankfully has no health issues. i hope it stays that way. he is deaf and can see at the moment but i have been told his pupils where different as a young dog than they are now so i wander if they will get worse. breeders if all pedigree dogs really do have a lot to answer for, they should have to pass a test to prove they know what they are doing before they can be allowed to breed, but then all animal owners should prove they can care for an animal. i dont suppose that will ever happen though,
   i dont know if these links will work but this is my merlin.
   tracey
   [IMG]http://i245.photobucket.com/albums/gg65/peggysmum/DSC_0135merlin.jpg[/IMG]
   [IMG]http://i245.photobucket.com/albums/gg65/peggysmum/DSC_0056mer.jpg[/IMG]
   [IMG]http://i245.photobucket.com/albums/gg65/peggysmum/doggiesinthesnow007.jpg[/IMG]

   
   
3. on March 19, 2011 at 8:38 pm bjarne

   It is strange that merle is only realy well established
   in the european hearding breeds and realeted dogs like the catahoula,all working dogs…wich is probably a good indication that the negative efects of the hetrozygot merle are more or less unfounded and/or based on homozygot merles.
   Why is it that only one breed from the molosser group (great dane) have it as a “old” established (not from recent crossbreeding) color.Would be interesting to find
   some historic info about the harlequine dane..but google
   was not very helpfull with that…

   
   
4. on March 20, 2011 at 7:07 pm Peggy Richter

   bjarne commented that merle “is only really well established in European herding (sic) breeds”…. and asserts that therefore it cannot be true that the heterozygote form is not harmful. That assertion is based on an erroneous assumption. It’s very possible that Merle originated as a mutation in some European herding dog. That would likely explain its occurrence in European (vice American or Asian) dogs or in herding dogs vice hounds, mastiffs, etc. However, the merle gene seems to be more prevalent in dogs of French/German origin vice “European”. Merle occurs in a number of UK breeds (BC, sheltie, collie, corgi, OES) — the UK breeds are not always lumped with the “continental” dogs. OTOH, one doesn’t see merle occurring in many Russian, Polish, Italian or Greek herding dogs. Non herding EU merle dogs include Danes, Dachshunds, Pincher (http://mmpinschersminiature.homestead.com/val.html). Keep in mind that it only takes one cross to “bring in” the gene and that active selection against merle can rapidly remove it from any given breed/landrace.
   As to the argument that since it exists in working dogs that it must not be a problem, alas, no. There are problems with the heterozygote form – see the Australian Shepherd Health & Genetics Institute site (http://www.ashgi.org/index.htm) there are several articles that discuss that there are more problems with eye defects and other issues with heterozygote merles than with non merle dogs. People kept the color because they liked it. The problems might not be so significant as to preclude a dog working yet still present a problem for the dog.
   Peggy Richter

   
   
5. on March 20, 2011 at 9:21 pm bjarne

   Sorry I could not find the articles you are refering to on http://www.ashgi.org/index.htm

   
   
6. on March 21, 2011 at 12:03 am Peggy Richter

   http://www.ashgi.org/articles/fact_eyes_cerf.htm–“Iris Coloboma–a missing section of iris. Almost all affected dogs are merle. A large coloboma will prevent the iris from dilating and contracting properly resulting in some discomfort and difficulty in bright light”
   Also see Light-Microscopic Investigations on the Retinae of Dogs Carrying the Merle Factor
   G. Klinckmann1,2, G. Koniszewski1,2, W. Wegner1,2,*Article first published online: 13 MAY 2010
   DOI: 10.1111/j.1439-0442.1986.tb00580.x –The nuclear and ganglion cell layers were badly differentiated and retinal folds and rosettes were found. None of the homozygotes had a Tapetum lucidum (T. l.) and only two of the heterozygotes had a T. l. and this has in only one eye in each case. Retinal pigmentation was scanty in homozygotes as well as in heterozygotes.
   There is also some concern about unilateral/bilateral deafness as merle tends to reduce pigment overall and when it affects the area around the ears may result in deafness.
   Peggy Richter

   
   
7. on March 21, 2011 at 3:43 pm bjarne

   Thanks ,not trying to argue to much about this subject,but
   I have yet to find any good sientific articel that defenitively
   shows functional problems in hetrozygot merles.

   “Iris Coloboma–a missing section of iris. Almost all affected dogs are merle. A large coloboma will prevent the iris from dilating and contracting properly resulting in some discomfort and difficulty in bright light. The condition is congenital (present at birth). Mode of inheritance is unknown.”
   That short bit of info about “Iris Coloboma”
   doesn´t mentions anything about if the dogs are homozygot merle or hetrozygot merle..

   The “Light-Microscopic Investigations on the Retinae of Dogs Carrying the Merle Factor” is better evidence,but,
   I can only read the summary ;
   It is a very small number of dogs and it does not mention how it was determend
   that the dogs where homo or hetrozygot merles;was it by
   dna testing or by phenotype?

   Well it was actualy some good informative discussions on the CanineGenetics-L@yahoogroups.com mailing list today
   about deafness in dogs with white patterns(with out merle)

   If we take the most poular “merle breeds” the Collie,the sheltie and the Aussie they all have white patterns.So
   how would you know if a hetrozygote merle with white
   pattern is deaf beacuse of the merle gene or beacuse of
   the white pattern?

   
   
   • on March 21, 2011 at 4:44 pm Christopher@BorderWars

     bjarne –

     Don’t expext a lot of “good scientific” information on this subject. (1) Many studies are funded by human medical research needs using corollary diseases in dogs. Humans don’t have Merle, so there’s not going to be a look at it any time soon.

     (2) Studies are also funded by breeds that want to get rid of a disease or to help breeders make better decisions, i.e. you pay for information that helps you change your behavior. In the case of Merle, I don’t see any of the established breeds even considering getting rid of it. So they are not likely to pay for research that will not benefit their current decision and only make them look cruel to have it at all.

     BUT… you really should go read my post. The second blockquote shows that Heterozygote Merles ARE affected with hearing loss issues.

     They also have the same eye problems. http://www.ashgi.org/color/eyedefects.htm “This dog is a normal merle, not a homozygous”

     In both cases the only comfort is that the single form is often attenuated, resulting in a lower percent of problems or problems of a lesser degree.

     Also, nothing really supports your assertion that Piebald is the only deafness causing white factor and that Merle is getting a bad rap because of it. Both cause deafness independently, but perhaps for a very similar reason, i.e. disabling pigment.

     
     
8. on March 22, 2011 at 1:55 pm bjarne

   Christopher,

   (1) Sure you are right about that!

   (2)Ok ,The second blockquote in your post:

   “Reetz et al. reported hearing results for 38 dachshunds (Tekels in German): 11 double merles, 19 single merles, and 8 non-merles. They found hearing loss – slight to total, unilateral or bilateral – in 54.6% of double merles, in 36.8% of single merles, and in none of the non-merle.
   …
   In an unpublished study performed by myself and these investigators at Texas A&M University,7 70 merle dogs from five breeds (Shetland sheepdog, Australian shepherd, collie, Great Dane, and Catahoula leopard dog) had BAER hearing tests performed and merle genotype determined by DNA tests. Of 22 double merles, 8 were bilaterally deaf (36%) and 2 were unilaterally deaf (9%). Of 48 single merles only one was unilaterally deaf (2%), a Great Dane that also carried the piebald gene”

   You realy nead to provide better references for quotes you make….(Who is “myself” in the above quote?)

   “Also, nothing really supports your assertion that Piebald is the only deafness causing white factor and that is getting a bad rap because of it. Both cause deafness independently, but perhaps for a very similar reason, i.. disabling pigment.”

   Well I would not call it an assertion..im just trying to get all the facts right -merle have been a very contoversial subject in some breeds…

   
   

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