Dr. Jeff reveals the cause behind a beloved senior dog's mysterious lump. A cat called Tigger is monitored for unusual eating habits. An owner learns the perils of purchasing her pup online after it becomes sickly, and Petra shows off her guinea pigs.

Dr. Jeff discovers a large mass on a loveable canine. Dr. Don helps Kelly the vet tech with her dog's sun-damaged nose, while Dr. Baier and Hector join forces to treat wild bison.