Advice from DNA geneticist re cryptorchidism

Hi Dawn,

With a small gene pool you will probably have to make the decision to move slowly, realizing that you can not throw the baby out with the bath water. The first goal should be to reduce the frequency (%) of affected dogs produced in each generation.

I would recommend culling out all affecteds as the first step. The when you get to the point that the incidence of affecteds is much lower (say like 10% of what it is now) and your gene pool is larger then you can start working on culling the carriers. (Maybe there will be a test by then?!)

So for the dog that is normal but has sired the occasional affected dog, I think you probably need his other genes. So I would recommend test breeding his offspring and making the selection on that generation. You could also use him to test breed females, which would allow you to pick the non carrier females to breed him to for the next generation and allow you to remove those carrier bitches that are not the best otherwise.

A slow, deliberate approach would probably work for everyone but they have to realize it is a multi-generation solution, not a one generation solution.

Dear Dawn,

Unfortunately we have already looked at the most likely gene candidates and found that these are not involved at least in the breeds we checked. This is not unexpected, as mutations in these genes account for only a few affected patients. In humans, they also do not know which genes cause the majority of cryptorchidism cases.

So that means it will take a different, more time consuming approach, but we have started collecting samples in many breeds. Therefore I do not expect a test to be available anytime soon, as the gene search is still very much ongoing.

My best advice is to remove any affected dogs from the breeding pool. Remember that some siblings (male and female) of affecteds will carry the genes too. So test breeding should tell you over time which dogs do. Look at this as a long term project, because it will take time to make progress in the absence of a DNA test, but it is worth doing!

I hope this is helpful to you and your breed club.

Vicki Meyers-Wallen