More on the CMSM and the BVA/KC Scheme
by, 19th January 2011 at 11:40 PM (2334 Views)
It has been very heartening to see how the complexities of CMSM are now being openly discussed.
There can be very few serious breeders that have not realised what an uncertain future the breed faces.
Many of us fear that it will prove to be too late to reverse what we have blindly bred into our dogs.
I hope we are wrong.
This is a beautiful breed, but public opinion is unlikely to condone the continued breeding of little dogs that face an increasing chance of a painful life.
Either breeders get behind the researchers and provide them with reliable information to work on or the breeders alone will be responsible for presiding over the destruction of this breed of loyal little companion dogs.
It is good to see that more discussion is taking place about the new scanning scheme, sadly some questions are not answered correctly, and so I thought I would make sure that everyone knew where to find the relevant information.
The leaflet for the proposed BVA/KC MRI Scheme is here.
Notes from the BVA /KC CMSM Scheme Seminar, which was held on 7th October, are on the Cavalier Club website.
For those worried about how long it will take to get the scans read, the notes include the information that there will be an anticipated 2 week turnaround.
For those who still believe there are a lot of cavaliers without CM, Clare Rusbridge noted that she has seen no CKCS without Chiari-like Malformation, only 2 with mild CM in the past 12 months.
The notes also include details of a talk given by Clare on some research, that is still being Peer Reviewed prior to publication, on the Interim Breeding Guidelines for Syringomyelia – 4 year report.
The notes state:-
This research is based on the Breeding Guidelines issued in 2006, using 465 dogs (CKCS and Griffon Bruxellois.
Full details cannot be reproduced here (as these are interim results that are undergoing Peer Review prior to publication) but a summary of the results:
The conclusions and recommendations of the INTERIM report:
- Offspring without SM only occurred when there was at least 1 parent of Grade A status
- There were higher numbers of SM clear offspring if both parents had Grade A status
- There was no influence of gender on SM affectedness
- All grade A* (where a grade of A* was assigned to Grade A dogs that had MRI aged 5 years or older) offspring had at least one Grade A* parent
- Higher numbers of A* offspring resulted from matings where both parents were grade A
- 100% offspring were SM affected if both parents were SM affected. The parents had often been bred before the SM developed
- SM affected offspring may also result from SM unaffected parents
- Using dogs of unknown status was risky for SM affectedness. 50% of older offspring were affected in A x U parental crosses and there were higher numbers of SM affected dogs with other parental combinations that included 1 Grade U (where Grade U is parent of unknown status)
To increase the number of SM unaffected offspring at least 1 parent should be ascertained to be free of SM by MRI at 2.5 years of age.
In ideal circumstances both parents would be free of SM at 2.5 years of age and the true SM status of the grandparents at least 5 years old should be established.
It is recommended that all breeding dogs from breeds susceptible to CMSM be MRI screened and results submitted to an officially recognised central database"
Read more about the scheme on http://www.cavaliertalk.com/forums/e...-KC-MRI-Scheme
For the more technically minded here is an intereresting new article from Clare's newsblog. It includes a cavalier family tree with breeding grades.
Morphometric assessment of cranial volumes in age-matched Cavalier King Charles spaniels with and without syringomyelia
C. J. Driver, C. Rusbridge, I. M. McGonnell, H.A. Volk
Veterinary Record 2010 167: 978-979 (short communication)
This study compared young Cavaliers under 2 years with SM (‘E’ breeding grade) with older dogs over 5 years without SM (A* breeding grade)
When Cavalier dogs of all ages were investigated for CM there is no difference between the volume of the skull (caudal fossa) of those that had Syringomyelia (SM) and those that did not have SM. However, when age was taken into consideration, the volume of the skull was significantly smaller in young cavaliers with early onset SM (under 2y) compared to cavaliers clear of SM over 5 years of age. Also the size (volume) of brain within the skull was significantly greater in SM cases and even greater in young dogs with early SM cases
Penny Knowler notes that the interim Breeding Guidelines advise that dogs with SM less than 2.5 years are not used for breeding.
If breeders wait until 2.5 years of age to MRI screen their dog they are given a ‘D’ grade if it has SM and it should only be bred to an ‘A’ grade dog. Many cavaliers are used as stud before they are 2 years old.
The late onset of SM poses a real problem for breeders. There is currently no grade distinction made between a young dog of 2.5 years and an older dog screened at 5 years of age with a minimal syrinx. This aspect will be addressed by the proposed BVA/KC MRI screening which will include a grading for both CM and SM to be used in conjunction with Estimated Breeding Values
Pedigree analysis suggests that the abnormalities producing CM/SM are inherited Black square/circle = SM affected male/female
White square/circle= unaffected male/female over 5 years
small circle = unknown status