It can be quite hard to tell if your bitch is pregnant but there are signs you can look out for. Most of these though are not apparent until she is quite far on into pregnancy. The average pregnancy for dogs lasts between 61 and 65 days.
You can look out for vaginal discharge, which will usually appear around one month after mating. Also, in preparation for feeding the puppies, her teats will become more noticeable at around 25 to 30 days after mating. You may notice her appetite decreasing from around day 25 to day 35 but not in all dogs or indeed all pregnancies. Your dog may seem less lively in some cases. The obvious sign of a fatter tummy usually isn’t noticeable until 45-50 days into the pregnancy. Nearer the due date some nesting behaviour should occur such as scratching at the floor or bed, and being increasing restlessness.
You will probably be able to tell if the mating has been successful about one month afterwards. If you do suspect that your dog is pregnant, you’ll need to see your vet for confirmation. Your vet will either do an ultrasound which is comfortable and non-invasive for your dog. Your vet can also test for relaxin, a hormone produced by pregnant dogs after about day 21. A physical examination or listening for heartbeats with a stethoscope is a cheaper option but it can be harder for your vet to detect the pregnancy.