The best part about Chase is the way he sneezes. He has a very powerful sneeze. It never changes but it is the same. The episodes where he sneezes are: Pups Save a Sniffle (s2), Pups Save a Chili-Cook Off (s4),
Pup-Fu (s2), Pups Save a Train (s1), Pup Pup Goose (s1), Pups and the Snow Monster (s1), Pup A Doodle Doo (S1), Pups Save the Queen bee (s2), Pups Save a Corn Roast (s2), Pups Save the Songbirds (s3), Mission PAW Quest For The Crown.
There is a video on Nick.Jr entitled Chase's Case Of Sneezes.