Hey peter frendo, Breaking in age can depend on the greyhounds maturity. The rule i was told years ago where about 15 months for a bitch and 17 months for a dog was the ideal age. Breaking in dogs in the cooler months of year is also a good idea. Anyway the decision is upto the owners of the greyhounds and there will be alot of debate from all different people when it is the right time to break them in. cheers Dougie