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Genetics question

Posted: Wed Dec 30, 2015 12:40 pm
by callalily
I have a female dog that is from a merle to merle breeding. The dog does not have any health issues. Testing on eyes is all normal or clear by parentage. The dog is being bred to a black tri. Will the offspring have any eye, ear or other health issues as the result of the merle to merle breeding of the grandparents?

Re: Genetics question

Posted: Wed Dec 30, 2015 1:56 pm
by jltruskey
No, the grandparents' merle-merle breeding will have no effect on the grandpups. The grandpups will not inherit more than one merle gene from those grandparents, and you said their sire has no merle gene for the pups to inherit. What color is your female? If merle, do you know if she is Mm or MM?

Re: Genetics question

Posted: Wed Dec 30, 2015 1:59 pm
by Shalako
Short answer is no. Merle is not a disease it is a color pattern. The eye defects and hearing issues related to merling occur when two copies of the merle gene suppress the development of pigment. Pigment cells known as melanocytes are necessary to develop many of the central nervous system processes like eye development and hearing. White related deafness can occur without the merle gene present and as part of the piebald/excessive white gene. as well as other congenital defects.

Please be aware that not all eye defects are testable by DNA and not all are able to be cleared simply because the parents are clear of a set of genes. We have a wide variety of defects that may still appear despite testing, including cataracts.