Ive personally found if they older than 5/6 then theres normally problems....put some money away for a c-section, would be my advice...
Last bitch was 9,11 died inside her,3 alive,knocked the weakest on the head at 3 days,it was f****d,wasnt fair...ended up with 1 dog,1 bitch...
If I ever bred another litter then id use a bitch,no older than 3/4..your bitch ,your choice