What is my beagle mixed with?

My husband and I just adopted a beagle mix from the pound and we're not sure what she is mixed with. She has the characteristics of a beagle (sniffs everything, chases squirrels, doesn't listen to us if we let her off the leash), but is longer and thicker than a beagle and has shorter, more triangular ears than a beagle. She weighs about 30 lbs. Here's a picture of her:http://i129.photobucket.com/albums/p236/alize339/0924091140a1.jpg