Taxi (1978) : 5x14

Alex takes ownership of his old dog, Buddy, who has been living at his sister's place in the country. Buddy is now 19 and Alex wants to spend as much time with him as possible. The dog is lovable but at his advanced age, requires constant care, and Alex soon is taking Buddy with him everywhere including the cab. The gang soon sees that Buddy is not doing very well and gently suggest that Alex consider putting him to sleep, but Alex refuses. Jim suggests that Alex get Buddy to do his old trick (playing dead) to determine his wellness. Buddy does the trick successfully, although gives the gang a scare when he doesn't get up right away and they really think he may be dead (thankfully, he turns out to be okay). However, the next time the gang sees Alex, he doesn't have Buddy with him, and Alex says that he had to take Buddy to the vet where he died. Louie ushers everyone out of the garage so Alex can grieve alone. With everyone gone, the stoic Alex cries as the episode ends.