If you have a pregnant dog at home, you'll probably notice immediately once the puppies arrive. But if you're dealing with a stray or rescue dog and want to know if she has given birth recently or in the past, it's not as easy. Luckily, there are some signs that might help you determine the right answer.
Look for the presence of puppies. This might seem obvious, but stray dogs are masters at hiding their pups. Try to listen for soft cries or watch to see if the mother keeps walking back and forth towards a specific location. Look for signs of "nesting" -- including torn-up newspapers or other soft material -- in small or crawl spaces, under stairs, in holes and other dark places where the mom would feel safe leaving the pups.
Another way to determine if a dog has given birth is to observe her behavior. For example, dogs who have given birth might seem irritable or more aggressive than usual. They also might snarl, bark or try to prevent a person or another animal from walking in a certain direction. This is usually to prevent the intruder from approaching the place where her puppies are hidden.
Enlarged breasts is a clear sign of late stage pregnancy in dogs. This usually indicates that the dog has given birth or is about to. A difference between the two stages can be seen by looking at the size of the belly. You should see a noticeable difference after delivery, since the stomach will look much smaller. This is especially true in stray animals, since they are more likely to be underweight; a change in weight before and after pregnancy will be very noticeable. Also look for signs of enlarged nipples or a discharge coming from the nipples. You also might notice a brownish-red discharge from the vulva for up to four weeks after delivery.
If you see no obvious signs of puppies, one way to verify if a dog has had puppies is to take her in for a veterinarian checkup. The vet can take an X-ray or an ultrasound to show whether the uterus is enlarged, a sign that the dog has given birth recently. In many dogs, the nipples remain stretched or enlarged after giving birth.