Hmm a difficult choice
I understand the dilemma but I am not sure I would still be thinking of breeding a dog so young just incase they became infertile early
You might end up breeding out the epilepsy but end up with infertile dogs and so loose the breed anyway

If things are really that bad would it not be better to freeze sperm and eggs from all the remaining dogs and see how they all turn out - then plan a breeding programme based on that? using surrogate bitches
I can see your dilemma, my head says if a breed is so far gone is it too late to save? But obviously there are people like you who love the breed and want it to continue, a difficult situation

To be honest it wouldnt help as far as epilespy is concerned it can lie dormant for years and there is no genetic marker so a line can go down overnight. lines seem I think freezing sperm is inviting a load more problems, were struggling at the moment to stop people breeding from dogs who have sired a fitter image if ewe froze sperm and then the dogs sired a fitter the implications dont bear thinking about.
To be honest its unusual for a welsh dog to be used under 16 months and at that point they tend to be more or less the finished product for example we knew at 12 months that spence temperament probs meant we would never allow him to be used at stud.
The main problem we are such a small breed was during the war there was only three or four main kennels and sadly the dogs were all destroyed.
To make matters worse a foriegn dog was exported a few years ago and because it was a new blood line it was used extensively, for some reason or another not least P. Eplisepy its offspring seem to die young or sire dogs with problems.