breeding dogs

Question
Hi Leigh-Anne
I want to  know how many years can you breed a miniature
Schnauzer female before it becomes dangerous for the dog to do so

Answer
Hi Terry...
Your question is not a straight forward age response,  so before I can give you a definitive answer there are moral and ethical issues to be addressed. As I don't know your circumstance or knowledge base,  I'll answer on the pretense that you are not familiar with breeding.
Firstly, I need to say this.straight up ...a dog is not a breeding machine for monetary gain. I, like all responsible animal lovers am against puppy breeding farms for monetary gain due to the abhorrent treatment those poor dogs endure.  Having said that, I'm not, in any way insinuating that's what you're doing however before a pet owner wants to breed they do need to do a lot of homework to ensure they can breed responsibly and ethically in the very best interest of the breed, bitch and pups and done according to your governing body for animal care and ethical breeding in your home town. Many states, council zones and countries have varying laws and regulations that cover ages, breeds, registering on mains or limited papers,  how, who, when, why and for how long breeding requirements for registered breeders. If one is not registered with the governing body known as "back yard" breeding.
The bitch needs to be in peak health because pregnancy, birth & feeding takes its toll on the dog. Have your vet do a complete medical, ruling out all genetic and Schnauzer related health issues, feed a top quality diet, home in a warm/dry/cool/ living environment, good human/animal socialisation, exercise and enrichment.  A happy healthy pet will manage the event far better.  Correct breeding is not cheap either. There are many ongoing costs involved until the last pup leaves for its 'forever home.
So..once homework, preparation  and registration complete, then you will be knowledgeable regarding your commitment.
Personally, if I can tick all the boxes above and more I still would not mate my dog until she was sexually, mentally and physically matured at around 2-3 yrs. Whilst a  female can go on heat and/or get pregnant very young, at 6-9 mths, generally first heat is around 12mths(although breeds do differ) But she's still a pup then herself and needs to enjoy herself. Then providing her pregnancy and birth goes smoothly with no complications, and the pups are bright, robust and developing well it would certainly be in her best interest to allow a good 12-18 mths between breeds and only 2-3 cycles.
My recommendation in mums best interest is approx 2 years, 4 years, 6 years stop. I've known bitches to have bred 6 mthly til nearly 9 years old but their lives were horrendous,  health very poor, raising pup and bitch mortality.
greatly.
So thanks for your question Terry, and I do hope this has assisted you.  As you can see there is a lot at stake and its not just a simple 'come together' and sell the pups, pocket cash and do it again. Breeding must be ethical and for betterment of the breed only as there are so many abandoned pups and dogs in this world and the health and welfare of your dog is paramount.
Cheers Leigh-Anne