Simpson and Wentz to visit 'Dog Whisperer'

That's the focus of an episode of "Dog Whisperer" on the National Geographic Channel.

Wentz and Ashlee Simpson had hoped getting Hemingway a dog friend would help. However, when they got a bulldog puppy named Rigby, Hemingway got aggressive.

The episode focuses on Dog Whisperer Cesar coming into their home to make it safe for the newborn. The episode airs Dec. 28.