Yesterday I finally got the grades for the dogs we took to Bristol at the beginning of August to be MRI scanned on the BVA - CM / SM scheme.
I must confess I find it a bit nerve racking when I get the Chiari-like Malformation/Syringomyelia (CM/SM) grades for the dogs. This is the one health test that Cavalier breeders fear and is why so many don't do this health test. In this envelope was also the grades for our first Brittany/Cavalier dogs done on the scheme. We have had a couple of our Poodle/Cavalier crosses MRI scanned on the scheme and disappointingly both have shown no change in Chiar-like Malformation, both being graded CM 2. Would we see any improvement on paper with using the Brittany?
Yes, we certainly have had a result using the Brittany with the Cavalier, both girls were graded CM 0, which followed that they were graded SM 0c. Their mother Smudge at 3 years and 5 months old was graded CM 2 and SM 1b. This shows that with one cross you can produce from a dog graded CM 2 offspring without CM. Below is a photo showing what the grades mean and breeding recommendations. You can also find this on the BVA - CM / SM scheme page here
Now for the results for Toby who is a pure Cavalier and his son Ernest who is 3/4 Cavalier and 1/4 poodle.
These results may seem not good, but in the context of the Cavalier breed, they are actually not as bad as they seem at a second glance. We have to be honest here, the Cavalier is not a very well breed. Toby when he was 3 years and 3 months was graded CM 2 and SM 1b, so we already new the CM grade was going to be 2, as it is for nearly all Cavaliers that have been scanned on breeding schemes so far Survey of 339 German cavaliers finds 97.1% with Chiari-like malformation and 48.1% with SM and on DR Clare Rusbridge's (Who is a leading Neurological vet) page explaining the CM/SM Grading scheme it says that in a 24 month period of 564 Cavaliers being MRI scanned for breeding purposes 0 received a CM o grade, only 6 received a CM 1 grade and 558 recieved a CM 2 grade a whopping 98.9 % were found to be CM 2. These figures are why I can see the only way forward for the Cavalier is using crossbreeding programs.
Toby has gone from SM 1b to SM 2a, but we have to look closer at this. SM 1 means the dog has some central canal dilation which is under 2 mm. Toby now has a dilation of 2.2 mm, so has only just breached the threshold between the two grades. He's borderline SM 2 and is not symptomatic.
Ernest's CM 2 grade is what I expected, although I hoped I might see a drop in the CM grade, but his Mum and Dad are both CM 2. He is SM 0c though and hopefully with the better skull shape with the 1/4 Poodle in him, he will be less likely to progress to have SM in the future, when he is re-scanned.
So what are the MRI grading of my dogs telling me? With having two Poodle crosses with CM 2 grades and now two Brittany/Cavalier crosses with CM 0 grades, it might be saying that the Poodle is not such a good option for using with the Cavalier. Admittedly, it has not on paper given great results, but using the Miniature Poodle (which is the middle sized Poodle) you can see it does improve the skull. It lengthens the muzzle and in most there is lengthening of the cranium. It also vastly improves the anatomy of the eye.
The Poodle has a Dolichocephalic ('long-headed) head and sits on the opposite of Brachycephalic (literally 'short-headed'), both these heads are extremes for dogs, although I would think being long headed causes less problems for a dog than being short headed and the mesocephalic ('middle-headed') head which we see with wild dogs such as wolves after millions of years of trial and error by evolution does the most efficient job for a dog. The Miniature Poodle is by no means an extreme long headed dog and one might reason that crossing the two extremes will put you somewhere in the middle. Yes, it does improve muzzle length, so the ability to regulate temperature and denture is better and a bit of length is seen in the cranium and we have better eye anatomy, so things are going in a better direction and we can see with Ernest who is the result of a first cross with a Poodle to Cavalier back to a Cavalier that those improvements are still kept in the second generation.
Using the Brittany spaniel which is mesocephalic ('middle-headed') though we have seen not only an improvement in muzzle length and eye anatomy, but we have seen a noticeable improvement in the length of cranium with the first cross and this improvement has been reflected on paper with our first two Brittany/Cavalier girls getting a 0 grade for CM.
So with our Brittany/Cavalier girls, we have no CM. The only draw back with using the Brittany is size, but I've always felt you would have to go bigger to tackle this problem and then come back in size carefully. That is now where Toby and Ernest come in.
With Toby being MVD clear over 5 years old and borderline SM 2 and still asymptomatic at nearly 6 years old, I think with Blottie being clear of CM this matching is still viable. We have shown with Blottie's parents that putting a dog with a mesocephalic ('middle-headed') skull on a Cavalier bitch that has a Brachycephalic (literally 'short-headed') skull and CM 2 and SM 1 grade can produce dogs without CM/SM. So there is a high probability that Blottie who is mesocephalic ('middle-headed') with Toby can also produce CM 0 dogs and using Ernest with Bumble (Blottie's sister) I would hope with that bit of Poodle in him will give an even higher probability that offspring can be produced that are CM 0. Unfortunately, the only way this can be found out is to breed the litters. I know though that the risk for these matings is far less for CM/SM than breeding any two pure Cavaliers together. So hold on to your hats the pairings stand. Blottie goes with Toby and Bumble goes with Ernest. This is going to be interesting.
“The greatest pleasure of a dog is that you may make a fool of yourself with him, and not only will he not scold you,but he will make a fool of himself, too.”
― Samuel Butler
Me (Jane) with Bumble and Blottie, waiting patiently to be unleashed, November 2018
Hello, I am Jane!