Trying find out if my dog is pregnant?

how long did the shelter have the dog?she could have gotten bred before the shelter got her if she is pregnant. a href="http://www.ehow.com/facts_4780273_early-signs-dog-pregnancy.html?ref=fuel&utm_source=yahoo&utm_medium=ssp&utm_campaign=yssp_art" rel="nofollow"http://www.ehow.com/facts_4780273_early-…/a