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inca
18th September 2008, 03:01 PM
is there any information on here to highlight the difference between MRI scanned grade A and a grade A CLEAR ......

inca
19th September 2008, 10:16 AM
anyone ?

*Pauline*
19th September 2008, 10:44 AM
I didn't know there was a difference, would be interested to know too.

inca
19th September 2008, 10:52 AM
I think its to do with the age of the scanned dog ...

Karlin
19th September 2008, 11:58 AM
Well, there actually isn't any formal definition or grade called 'A clear' -- no neurologist offering scans uses this term and it isn't a recognised grade. At one time there was a grade called A* -- which meant clear of malformation, clear of SM -- but so few dogs fit this, and also, the malformation could be a matter of dispute between some neurologists not that familiar with seeing it in dogs -- that the neurologists panel at the London SM conference in 2006 voted to eliminate that category. This was a somewhat controversial decision but the neurologists felt it had become a meaningless category.

On age: all grades used for actual breeding decisions are only given to dogs 2.5 or older. So in a way, age is only relevant in two grades -- C or E dogs. These grades reflect scans on dogs under 2.5. Neither grade should be bred until rescanned at 2.5 or older. So C or E is only an initial marker scan but can never be assumed to be the dog's actual grade. Dogs don't automatically transfer at age 2.5 to what might seem the equivalent grade for a dog 2.5 or older, as a grade can change a lot in those first 2.5 years and as with MVD you need a dog's status at the time of breeding, for a progressive condition, not way in advance of the breeding. The 2.5 year scanning age fits with the MVD protocol -- as with the MVD protocol, specialists felt that the older the dog when tested, the better and more accurate the grade will be for a longer period, but 2.5 is the best compromise they can recommend between best for health, and what suits breeders on breeding timescales. As with MVD, waiting til age 5 and scanning or heart testing is better than doing it and breeding before then but breeders are reluctant to wait that long before breeding.

With low cost club-supported scanning in the UK costing only £100 per dog, in this region at least, scanning is not a highly costly venture.

An A dog can still have very mild syringomyelia (almost all A dogs have the malformation -- keep in mind that neurologist Geoff Skerritt has MRId closing on 1200 dogs and of those, fewer than three dozen have been what would have been A*, without the malformation or SM).

Some have started to use the term A clear to mean A dogs without a syrinx -- that is my understanding of the term. Initially, A* dogs were sometimes called clear/clear dogs, but as noted, they are extremely rare.

Researchers and breeders are desperately hoping the genome scan will not reveal a type of inheritance where ONLY A* dogs may be bred if SM is to be adequately addressed. This would mark the end of the breed as it now stands, if that is the case. A lot is riding on the mix of the Canadian genome project and what Sarah Blott can predict using the genome results married to estimated breeding values.

The table for grading is here (http://sm.cavaliertalk.com/breeding/breeding/breeding.html).

inca
19th September 2008, 06:40 PM
Some have started to use the term A clear to mean A dogs without a syrinx -- that is my understanding of the term. Initially, A* dogs were sometimes called clear/clear dogs, but as noted, they are extremely rare.



thanks karlin explained so its important when wanting to perhaps use a grade A stud to see the scan results first ...
thanks well explained :)

Alison_Leighfield
19th September 2008, 06:55 PM
I always thought that an "A" was without syrinx but with or without a malformation and an "A clear" was without syrinx, dilated ventricles, central dilatition, hydrocephalus and only a very mild malformation. Maybe it's a term used but not within the grading system?

If the above two examples are both known as "A" there is a great difference between the two.

Glad to have this cleared up :)

Alison.

inca
19th September 2008, 07:21 PM
I always thought that an "A" was without syrinx but with or without a malformation and an "A clear" was without syrinx, dilated ventricles, central dilatition, hydrocephalus and only a very mild malformation. Maybe it's a term used but not within the grading system?

If the above two examples are both known as "A" there is a great difference between the two.

Glad to have this cleared up :)

Alison.

thats what i was told an A clear is better to have than an A