Dogs are discreet about mating and pregnancy. Without careful observation, you may not realize your beagle is pregnant until she is close to giving birth. Early detection of pregnancy can help ensure your beagle gets the proper care. It will also give you time to prepare your home for a littler of puppies. Pregnancy symptoms in dogs are similar to pregnancy symptoms in humans. Gestation typically lasts 57 to 72 days in beagles, according to the U.S National Library of Medicine (http://www.ncbi.nlm.nih.gov/pubmed/6685444).
Pay attention to her sleeping habits. If your beagle appears to be more tired than normal, it may be an early sign of pregnancy.
Watch her food bowl. A beagle in the early stages of pregnancy may have a loss of appetite. Later in the pregnancy, she will likely eat more than usual.
Look at her abdomen. As your beagle progresses in her pregnancy, you will notice her abdomen swell. This will continue as her puppies to continue to grow larger.
Check her weight. A pregnant beagle will eventually gain a noticeable amount of weight in areas other than the abdomen.
Look at her nipples. As she begins to prepare for nursing, your beagle's nipples will become enlarged. This will be a very noticeable change.