First Three Weeks
During pregnancy, a dog will exhibit both physiological and behavioral changes that better allow her to carry the pups effectively. The area around her abdomen will swell, and her body temperature will increase slightly, so she'll feel warm most all the time. Behavioral changes are often the first sign of a dog's pregnancy, and often a bitch will exhibit a complete turnaround in temperament. For dogs who are affectionate, they may develop a loner's attitude, while a dog who is traditionally aloof may become annoyingly affectionate. Changes in appetite will become apparent almost immediately. A dog who has been recently impregnated will typically lose the majority of her appetite for the first few weeks of the pregnancy. However, beginning around 3 weeks after the impregnation, the dog's appetite will likely increase dramatically. Monitoring appetite can be an excellent way to measure how far along your dog is, since the further into pregnancy she moves, the heartier her appetite will become. Beginning a few weeks after impregnation, the dog may begin to suffer nausea and upset stomach. Much like many human pregnancies, this morning sickness can occur at any time of the day or night, and typically lasts for the first third of the pregnancy.
Second Three Weeks
Beginning around the fourth week, the dog's breasts may become enlarged and she'll begin her nesting behavior. You may notice that she'll begin stockpiling blankets, pillows and old clothing in a little-used corner of the house. She'll begin sleeping significantly more, and sleep may consume as much as 18 hours of her day. While she's awake, she'll typically be resting. She'll become restless, and move frequently, trying to get comfortable.
Nearing the Birth
Vaginal discharge typically occurs beginning during the fifth or sixth week of pregnancy, and will continue until she enters labor around the 63rd day after impregnation. Around the same time as the vaginal discharge, she may begin producing copious amounts of milk. Less commonly, dogs may fail to produce milk until the pups begin nursing. The puppies will be easily visible beginning around the sixth week, and after exercising your dog you may be able to easily see them kicking, and will certainly be able to feel them through her abdominal wall. Birth will typically occur between 60 and 65 days after the bitch becomes pregnant, and can last several hours.