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How to know when to stop breeding a male dog
Consider your dog's age.
When deciding whether your dog should continue breeding, think about how old he is. Most male dogs can breed until they are senior dogs, but it is difficult for older dogs to get females pregnant.

Select from: [I] Compare your yorkie with other breeds. Ask what the other dogs in your household are like for a comparison. [II] After your dog is around 10 years old, you may want to stop breeding him. Some believe that certain small breeds shouldn't be bred after age seven, while other breeds can be bred up to age 12. [III] It's important to understand that early maternal quality in your dog is still established based on the breed and culture. Parenting can carry the same risks, and becoming a wife or a mother can be a huge shock to either dog. [IV] Consider your dog's age when deciding whether to stop breeding your dog. Older male dogs are more likely to breed than female dogs; however, it is hard enough to breed your dog if he is a year or two younger.
[II]