When your dog goes into labor, she has to actively push her babies out of her body. Because she may take breaks up to three hours long between pups, though, you should be able to identify whether or not she is pushing. This way, you can be there for the delivery.
Signs of Pushing
During the first stage of labor, your dog will start experiencing contractions and her water will break. This period is marked by restlessness, nesting in the whelping box and panting. When she is pushing, though, her behavior is notably more strained. Her panting will go from consistently shallow to deep, gulping breaths. You will also notice her abdomen straining, expanding and contracting as she uses the abdominal muscles to help push out the pups.