Screwed the Pooch is episode 13 of family guy season 03. It was originally aired on November 29, 2001.
When Brian joins Lois and Peter on their visit to the Pewterschmidits, his pent-up sexual energy is unleashed on the Pewterschmidit’s dog Sea Breeze. After the vet informs them that Sea Breeze is pregnant, Mr. Pewterschmidt refuses to let Brian near her. Brian decides to sue him for custody of the puppies.