If your pregnant dog starts dripping milk from her nipples, the puppies will arrive soon but delivery could still be several days away. Milk production is just one clue that birth is near.
As your dog's pregnancy continues, you'll notice changes in her mammary glands. Her teats start swelling as her due date draws near. You can gently squeeze her nipples a day or two before she's due to see if milk leaks out. However, some dogs don't produce milk until after the puppies are born.
Your dog might start leaking milk anywhere between one day and one week before delivery. First-time mothers often leak milk for longer, so if your dog has had puppies before, the start of milk leakage means she's likely to deliver within a day or two.
Taking Her Temperature
A more reliable way to determine when your dog will go into labor involves taking her temperature rectally twice daily. Normally a dog's temperature ranges between 100.5 and 102.5 degrees Fahrenheit. When your dog's temperature drops below 99 degrees, she'll go into labor within 24 hours. Start the temperature-taking routine about a week before she's due, or day 56 of the pregnancy.