I speak only as an owner that has had 2 litters - Not a professional breeder or Vet! Our 7 year old female has had 2 beautiful litters in the past year - we had only wanted one - but were slow on spaying (that is happening today). We own both male and the female. Both litters were very healthy, and all went to great homes! We supplemented her diet with vitamins and extra proteins during pregnancy and nursing. All has gone well - but will say the second litter seemed to put a lot of weight on her forelegs causing a bit of turnin - she has regained her strength and movement - it was a clear sign to stop.