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Originally Posted by Mardelin  Was reading on the web on how Dr Tobias came up with her figures......since the majority of her research was conducted on yorkies.....she used several data basis, one breing Breeder's Standard (coefficients). I'll see if I can find the link again. |
I think this might be what you were referring to, Mary. After reading it, I still don't get the conclusion since Dr. Tobias cites the odds ratio from her research in using the 35.9X greater chance for Yorkies having LS. In her research, the Havanese has an odds ratio of 64.9 while the Yorkie has an odds ratio of 58.7. It's still a head-scratcher for me to see how she came up with the figure unless she excluded the Havanese. Anyway, here it is....
"A hereditary basis for congenital portosystemic shunts (PSS) in Yorkshire terriers was explored through record and pedigree analysis and a breeding trial. The odds ratio for PSS in Yorkshire terriers was 35.9 times greater than for all other breeds combined. Wright’s coefficient of inbreeding was approximately twice as high for Yorkshire terriers with PSS as compared to normal members of the breed (P=0.09). No common ancestors were found that were significant to the PSS group. Two affected Yorkshire terriers were bred and produced two normal puppies. Congenital PSS appears to be hereditary in Yorkshire terriers; however, the mechanism of inheritance has yet to be elucidated."
...and here's the link
Determination of Inheritance of Single Congenital Portosystemic Shunts in Yorkshire Terriers -- Tobias 39 (4): 385 -- Journal of the American Animal Hospital Association
To me, the statement conflicts with the research still but I accept it for what it is.
Ladymom, I wasn't attacking you in my earlier post but I think you can see my point just as I can see yours. LS is the big bug-a-boo for the breed, to be sure. I'm not sure I would have ever gotten my first Yorkshire if I had seen that statement early on. The actual data is concerning enough but that one statement is downright alarming taken by itself.