The Transportation Security Administration found a small dog inside a carry-on backpack when going through the X-ray machine at an airport in Wisconsin.TSA officials told sister station WISN that the passenger was unaware of the screening protocol and did not tell security officers about her dog.After an officer explained the proper process and confirmed that she disclosed she was traveling with a pet to the airline, she proceeded to her gate. "A dog was accidentally sent through the X-ray" at the Dane County Regional Airport in Madison, Wisconsin this week, the TSA said on its verified Great Lakes region Twitter account on Tuesday afternoon.Animals need to be removed from carrying cases and the empty carrier sent through the screening machine, the TSA said."When traveling with any animal, notify your airline & know their rules," the agency said in its tweet.