
Hi saoirse
apart from the KC frowning on - and I'd wager completely banning - this procedure, I strongly suspect the RCVS would deter vets from performing it on the grounds that it has no physical benefit to the dog itself.
Unscrupulous breeders or exhibitors could in effect dupe someone into using a male at stud that is carrying this inherited defect - it's things like that which lead to breeds having seriously compromised breeding issues and difficulty establishing which lines are carrying the fault or are genuinely clear of it.
Hopefully in the case of your dog it will descend again naturally :) As others have mentioned it's not unknown for youngsters to retract the testes at shows only for them to appear again when less stressed or perhaps temperatures / weather conditions more to their liking LOL.
As for still showing him in the near future I'd say go for it up to open show level to give you both practice in the sights, sounds, scents and dog dense experience that can't be recreated at training classes. Some judges may penalise him and others be more forgiving at such a young stage - after all he might not be the only male puppy in the same situation and even if he is could still be of better breed type and conformation than the competition!
For your breeder's benefit, regardless of the outcome, please let him/her know what's happening and the eventual outcome as they will need to be aware there is a potential problem for future assessment of breeding stock.
Good luck meantime,
Teri :)