how old

[chealsea]

how old can a yorkie be until she can have a litter

[savraj_uk]

All female dogs should be at least one and a quarter years old before being pregnant. The preferred ages by the Kennel Club though, are from 2 years to 6 years. After 6, dogs shouldn't really have babies.

[Dr Doolittle]

Any canine bitch that has not been speyed continues to have 'periods' for life. Canines do not have a natural menopause like humans. However I would advise that no canine bitch is covered for breeding after the age of seven.

Having read it again, the wording of your question could mean two entirely different things, i.e. how old can they continue breeding until? Or how young can you begin breeding from them. If it was meant the second way, again in my opinion, no canine bitch of any breed should be made to produce a first litter until at least 2 years. In other words canine bitches should ideally only breed for five years, i.e. between the ages of two and seven.