View Full Version : Anyone know?
16th March 2008, 08:58 AM
If you have scanned your dogs before breeding on them - and they have no sign at all of SM - does that mean that the puppies not will have SM?
16th March 2008, 11:10 AM
Hmm, if both parents have clear MRI scans for SM then you would have a much higher chance of the litter being clear too. HOWEVER, the one thing that the scan CANNOT tell you, is if they are carrying the genes that cause SM recessively or not, 2 MRI'd clear dogs could both be carrying those genes and produce affected pups, this is the biggest gamble with breeding really, you have to be really sure of all the dogs for at least 5 generations back on both sides as they will hugely influence what your litter will inherit. Also if you are line-breeding then you have a much reduced gene pool to play with, but if you are outcrossing you will increase the potential gene pool but be very wary of what you might be bringing in, breeding is a huge game of chance at the end of the day!!
Hope this Helps?
16th March 2008, 01:59 PM
does that mean that the puppies not will have SM?
The short answer as Cathryn notes, is NO. This condition is so widespread in the breed now that genome researchers could not even find enough totally clear cavaliers (clear of the malformation that causes SM, and SM itself) to form a crucial clear genetic group that would help them find the responsible genes in affected dogs. Almost every cavalier has the malformation, which causes the skull to be too small for the brain, in different degrees of severity. They have had to go to a totally different breed that also has SM in smaller numbers, Brussels Griffons, to find the clear control group for the very important gnome research now taking place in Canada. You can read more about where this research stands here (http://sm.cavaliertalk.com/research/research/winter2007/winter2007.html).
What that means is that as with MVD the genes for the condition are likely permeating nearly all cavaliers so almost any mating is going to pass along some of those genes. What isn't understood yet is the mode of inheritance -- if it is a polygenetic trait (eg requires several genes to combine to produce affected dogs) as researchers believe, then which genes or possible environmental influences trigger more severe cases?
What initial research has shown is that A grade dogs -- no syrinx -- tend to produce almost no affected and symptomatic dogs, and the highest number of A graded puppies (though these have not been tracked across a full lifespan as this work is only a couple of years old now). Also, scans of family groups have shown that A grade dogs tend to be closely related to other A grade dogs -- find one A grade dog and you'll probably find others amongs parents or siblings or offspring. So scanning has enabled breeders to find other A dogs very successfully in the Netherlands (instead of just randomly scanning in the hopes of finding As), where they are very organised in doing such research (sadly no other breed clubs are pursuing this type of research at this time though the UK club is sponsoring research to get clearer breeding guidelines). There are known, affected offspring however from AxA matings but not many. Statistically this is always possible.
Asymptomatic but affected dogs (that turned out to be D grade or eventually symptomatic) have so far produced NO A grade offspring and a significant number of low grade dogs.
You can listen to a free podcast of Dr Clare Rusbridge explaining the condition and this research here: http://sm.cavaliertalk.com/rusbridge.mp3
You can buy two CDs of all the talks (aimed at a general audience) at the recent conference on SM in cavaliers in Rugby, UK here: http://www.cafepress.com/cavaliertalk/4311456
Personally, I would now want scan grades for both parents and to discuss overall breeding programmes before buying any puppy.
16th March 2008, 08:20 PM
Thank you for your answer. It is very interesting to hear what you think about this question. I am not a breeder but what I now it is not common to scan before use a dog for breeding. (In Sweden) We are still only talking about the heart, eyes and knees.
Is it common in your countries?
Even if you can't exclude that scanned and free parents will have puppies that will have SM one day, it gives a very good hint.
16th March 2008, 10:38 PM
No, it isn't common in the UK, US, Canada, Ireland or Australia, and indeed, meets a lot of resistance. The Dutch breeders have been the most active and are producing the most practical information.
Recently Brussels Griffon breeders have become very proactive about this condition in their breed clubs particularly in Australia and the UK and have already organised support for screening and research even though their breed is far less affected.
I would not be surprised if Swedish breeders eventually take a lead role in SM screening as they already have the most health-focused breeding requirements of any club, anywhere in the world. They are the only club to require basic health testing for registered dogs used for breeding registered puppies.
17th March 2008, 06:02 PM
"Asymptomatic but affected dogs (that turned out to be D grade or eventually symptomatic) have so far produced NO A grade offspring and a significant number of low grade dogs."
Karlin, you give such sound replies that I usually just read, but I was a little confused when I read this part of your response. I though I'd clarify for others a little slow like myself.
A 'D' grade dog paired with another 'D' will not ever produce an 'A' grade . . . but a 'D' grade dog paired with an 'A' can produce 'A' grade pups (and D's as well). This was how the Dutch initially started, because they did not have enough 'A's for A x A pairings. It is also the reason that the protocol allows A x D pairings. The loss in breeding population if every D grade was pulled from breeding, at 70% syrinx rate, would cause a huge bottleneck and create a mess of our breeds diversity if this was the route taken -perhaps raising the risk of many other yet uncovered difficulties cropping up.
Of course A x A most consistently produces A grade pups, but I know the percentage I've heard tossed around on that is significantly lower than 100% of the time.
For those reading and looking for pups, please keep in mind that a pup produced from an A x D pairing may end up with syrinxes but still has a significantly better chance of having no symptoms than a pup produced from a D x D pairing - as this problem seems to worsen generationally. Breeders using MRI are having to make breeding decisions not only for their own kennel, but for the good of the whole breeding population.
I'm sure we'd all love to see no SM and no symptoms, but that is going to take some time, a lot of conscientious breeders, and probably a gene test.
Arlene and her three
17th March 2008, 06:17 PM
Thanks for the post. I think on reconsideration that you have this right. I'll have to go back and check the podcast and my notes -- I had recalled that Clare showed no A dogs from any crossing with a D, but I may well be confusing this and that it was actually that no mating that DIDN'T include an A dog produced any A grade offspring. In other words a DxD or DxF. That's an important point. :thnx:
18th March 2008, 07:30 PM
You are completely right! I went back and reread my notes and listened to the talk. Thanks for the clarification. :thmbsup:
19th March 2008, 06:16 PM
Thanks for checking Karlin. :cool:
For the original poster, and anyone else who really wants to delve into SM studying, it was mentioned in the winter newsletter that research is continuing into correlating head shape and SM - but this time not by simple observation as was used before (unsuccessfully). The researchers are checking out x-ray results and comparing them to MRI.
So far (this is just initially) there seems to be some evidense that x-ray can give you some indication about symptomatic SM risk. The more domed headed, flatter back skulled Cavs seem to have more risk of symptoms (CM is an aggravant possibly?) Here are some links to some interesting pages about this.
I know if I were breeding I'd be keeping up on this ongoing head shape study. Even as a pet owner I'm very interested . . . but then I hope to breed in the future.
The correlation between CM and SM is not always what it would seem, though, as sometimes even mild Chiari and a lengthy skulled dog will come up with SM (this is a gene problem after all), so for breeding purposes MRI is imperative.
I have a Cavalier pet who shows no symptoms of SM, but I worry, so for myself, with MRIs here being $2500+ and impossible to book without a sick dog, I took an x-ray on my guy just to see where he stood by head shape. :thmbsup:Now I'm quite happy that I took the big headed pup, even though my hubby still teases me about it!:D
Arlene and her :paw: three :paw:
20th March 2008, 08:59 AM
...also just a point to think about as well,
SM is progressive and onset can be at any time.
No dilation one year can be quite moderate the next, likewise symptoms and a syrinx. Perhaps regular scanning on a 2yr period would be a good idea? especially for breeding stock. This would give a little more genetic history to work with as well?
24th March 2008, 07:13 PM
Alison: "No dilation one year can be quite moderate the next, likewise symptoms and a syrinx. Perhaps regular scanning on a 2yr period would be a good idea? especially for breeding stock. This would give a little more genetic history to work with as well?"
This is something I've thought about as well. As far as I've understood to get grade A the dog may actually have a dilatation as long as it is under 2mm. Isn't it then possible that the dog would get a grade D when scanned a few years later, if it has a dilatation of 1,9 mm at the age of 2,5 years? What would then be better from a breeding point of view: a 2,5-year-old dog with a dilatation of 1,9 and grade A, or a 10-year-old dog with a dilatation of 2,1 mm and grade D? I'm still studying the matter, and am not quite familiar with all these gradings etc.
Luckily we have the possiblity to scan our dogs now in Finland. The scan costs 400€ including a BAER-test and the Cavalier club supports the scan with 100€, so the owner has to pay 300€. The club also invited the 6 most used studs and paid for their scan entirely.
24th March 2008, 07:33 PM
I don't normally post in this section but this point "The more domed headed, flatter back skulled Cavs seem to have more risk of symptoms (CM is an aggravant possibly?) Here are some links to some interesting pages about this. " captured my eye.
Is there evidence that SM is a rollover from the breeding with pug etc which made the more dome head of the King Charles and that perhaps in future years IF RESPONSIBLE breeders attempt to produce more flat skulled cavs then this possibly lead to an eventual eradicatiomn of this disease/malformation.?????
Please exscuse my ignorance on this as I am hopeful that my two are clear of this debilitating illness and as such I do have a tendancy to stick my head in the sand. At present I have a 3 yr old and a nearly 2 year old that appear to be sympton free and :xfngr: they will stay so:paw:
My heart does go out to guys that are having to deal with this with their furbabies I send many:hug:s to you all :paw:
24th March 2008, 10:31 PM
"The scan costs 400€ including a BAER-test and the Cavalier club supports the scan with 100€."
I don't know what 400€ is equal to in Canadian currency. Can someone do the conversion for me? The Canadian and American dollar are almost at par.
In trying to encourage breeders here to scan I have made numerous inquiries about the process of getting a dog scanned and the price. It is phenominally hard here (Alberta, Canada) as we have a shortage of radiologists (for the last 20 years), and the scan comes at a $2500 starting price tag, with then the initial vet visit and mandatory overnight fee on top of that. If you get a booking for a breeding dog (not sick) you can be bumped - and since the scanner is a 7 hour drive that would be more than off putting. It really irritates me that there are so many road blocks here to getting a scan. This is for humans too, as my mother and brother both waited forever for their MRIs diagnosing Parkinsons.
I do think that the saviors of this breed are going to be the ones who can scan, and who can afford to scan more often than once per dog.
For Merlinsmum, there are many other breeds already known to experience SM. This is the list I have found.
Cavalier King Charles Spaniel
King Charles Spaniel (English Toy)
Staffordshire Bull Terrier
Anecdotally, on line I have also heard of SM in a Papillon.
SM seems to be caused by a gene that is behind many of the small breeds, and the Cavalier breeders - unknowingly and unfortunately - seem to have selected for it while selecting other traits. Some breeds seemed to have achieved the domed head shape from a different selection of safer genes.
Keep in mind prior to the 1850s breeds were not commonly bred pure. I have read Japanese Spaniel, Pekingese, Pug, Bulldog, English Springer Spaniel, Cocker Spaniel and Papillon all have played a part in the King Charles Spaniel and Cavalier King Charles Spaniel breed at different times.
Arlene and her three.
25th March 2008, 07:57 PM
400€ is about 627 Canadian dollars, and 300€ is 470 CAD.
25th March 2008, 10:05 PM
Thanks for the conversion . . . I just wish we could see those prices here.
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