While there isn't a specific episode titled "Meow Wow", the scene you're referring to likely comes from the episode "The Cat Concerto" (1946).
In this episode, Tom (the cat) is trying to catch Jerry (the mouse) who is hiding in a birdcage. The dog, Spike, is protecting the birdcage and, in a humorous scene, Tom tries to get the bird while Spike watches with a disapproving growl. Tom even says "Meow Wow" in this scene, imitating the bird's chirping.
It's not clear if Tom actually takes the top of Spike's ears and gives him a "which" in the scene you're describing, but it's a common gag in Tom and Jerry where Tom suffers some form of comedic punishment at the hands of Spike.
There are other Tom and Jerry episodes where the dog, Spike, protects the birdcage, but "The Cat Concerto" is the most likely candidate based on your description.