Here are some factors that can influence when a dog stops having puppies:
* Breed: Some breeds are known for having shorter reproductive lifespans than others.
* Health: If a dog has health problems, it can affect her reproductive ability.
* Spaying: If a dog is spayed, she will no longer be able to have puppies.
It's important to note that dogs can still go into heat (estrus) even after they've stopped having puppies. This is why it's crucial to continue spaying your dog after she's reached her senior years.
If you have any concerns about your dog's reproductive health, it's always best to consult with a veterinarian.