Last night my 4 month old was very excited and ended up humping the air ( all the way! )
This got me thinking , I wonder what is the youngest you've heard a dog sire a litter . I was thinking something like 6 months . I've never had a dog which wasn't neutered before , I usually just keep bitches , so I'm lacking info on the dog side of things. :)
I'm going to have to keep him separate from one of my bitches as she is due in heat in the next month or two as she isn't a bitch with a regular cycle.

not sure what the youngest is but ive known a dog of 8 months sire a litter

5 1/2 months - produced 1 puppy. This was long ago in the days when our breed had no health checks & a desperate shortage of stud dogs!

at 8 months his litter was 14 so i think he will allow them to copulate again

8 1/2 months

5 months. Next doors lhasa apso mated her bischon.....7 pups in litter. She ignored warnings & went on to have 2 more litters. Thats when i stopped offering advice...

4 1/2 months papillonxsheltie owned by mother in law caught sister in laws cocker spaniel, 2 pups resulted.

4 1/2 months blimey that is very young !

This is why it is so important when you keep a dog pup to separate him from Mum when she comes in season after the litter, as son x mother matings at this sort of age have been known to happen much to the owners dismay, and of course now the pups can't even be registered, so if they are not caught in the at and a mismate injection is nto given you have a litter of unregisterable pups on your hands..

gosh that is informative... I did not realise how lucky I have been ..just looked after my friends boy for a couple of weeks, the week before he arrived all my girls were in the last week of thier season  all together... a week later and I would have been tearing my hair out...I would have kept them seperate ,'just in case' but if I am honest I would not have not seriously thought he was old enough to have mated with them, although my breed are slow to mature.