A female dog’s gestation is about 63 days in duration, give or take a few days. Each of three 21-day trimesters brings physical changes to the mother as the puppies grow and develop. Your vet is a good source of information during your dog’s pregnancy and can help you understand the types of bodily discharges that are normal, and those that are cause for concern.
In the second trimester of your dog’s pregnancy, you’ll start to see noticeable changes to her mammary glands. Her breasts may become swollen and engorged and the teats darker than normal. During the later stages of pregnancy, right before birth, you may notice a milky discharge from her teats -- this is the early stage of lactation and is perfectly normal.
During the early stages of labor, your mother dog may appear restless, have little appetite and may even vomit. According to UC Davis School of Veterinary Medicine, as uterine contractions intensify and dilation progresses -- a process that can last from 10 to 24 hours -- your dog may have a vaginal discharge that should be clear and of a mucus-like consistency. If you see a greenish discharge and no puppies emerge within a few hours, contact your vet.
As your dog prepares to give birth, you will see the emergence of fetal tissue. This discharge you’re seeing is the membrane that covers the puppy as it is pushed through the birth canal. If the membrane bursts on its own, there will be a watery discharge. If not, the mother will bite through this tissue after each pup is born, bite through the umbilical cord and clean each pup. She will expel a placenta for each pup as well, and may attempt to eat the discharge, but it’s preferable that you remove as much of it as you can, or she may get an upset stomach.
Following birth, your mother dog may have a reddish-brown or green vulvar discharge for a few weeks. As long as the discharge doesn’t smell bad, this discharge is normal and expected. Allow the dog to clean herself and replace bedding or towels frequently to ensure she and her pups are dry, warm and comfortable. If the discharge has a foul odor and the mother appears listless or unwilling to nurse, consult your vet.