
A dog I bred was 6 1/2 before siring his first litter, then had a happy 18 months and sired 5.
The sire of my current litter didn't sire his second litter until he was 7 (in numerically small breeds often good males are too closely related to the girls their own age and need to wait for the next generation of bitches), he is 8 now, and I am sure is not done yet.
A friends Champion male mated his first bitch at just turned 7 and they are 6 weeks old and hopefully he will be the sire of my next litter.
So no I would consider a dog of 7 in his prime, especially in a small breed.
Barbara and the Grey Curly Tails.