Can anyone advise how likely it is for a dog to sire pups with glaucoma when the dam's grand sire has glaucoma ? This is in border collies.

You would need to know the mode of inheritance which I suspect for your breed as in common with many unknown.

Our breed has Open Angle Glaucoma so no predisposition that you can test for, they could be fine one day and develop symptoms the next.

I certainly would not use a dog whose grand-sire was affected, or if I had stock from such a dog I would avoid having affected, or dogs producing affected dogs on both sides of the pedigree

Thank you, you have just confirmed to me what I was thinking

The latest advice from the ophthalmic specialists is not to breed from any dog that has not been Gonioscopied normal nor from a dog that has been tested & found to be either affected or with a pre deposition to develop Glaucoma at a later age.

Most responsible breeders are not breeding from dogs who have affected dogs in their pedigree. even is they have been tested normal. Alan Wilton(in Australia)has already started research