I have to agree with Shot, i have a Border, went to ground to fox at 10 month's old, came out after 5 or so minutes and her litter sister went straight after her. I was talking about the incident with the bloke i got her off in the week, nearly 9 years ago the other day.
My bitch's mother was forward, so they say, for a Border, working her first fox at 14 month, my bitch and her litter sister both "worked" their first foxes around this age as well.
At the time i had a Border dog, big strong, powerful head and stupid, he was also at it early and never gave ground.
I had 2 litters ou