How long does it take before you can tell a dog is pregnant?

Generally, a dog’s pregnancy becomes visibly apparent around 45 days. At that point the abdomen noticeably enlarges, the mammary glands swell and may even leak milk, and the dog shows increased appetite, weight gain, and more frequent urination. If the litter is small – only one or two puppies – the increase in belly size may be less obvious. During pregnancy, make sure to provide enough nutrition, especially protein and calcium, to prevent adverse reactions from calcium deficiency after the puppies are born.