In Episode 120, Kurt accidentally leaves Wolfie sitting down after feeding him and wanders off without him, not realizing his mistake until night has fallen and he's planning to dig a hidey hole and end the episode. What changes this from a Tear Jerker to a CMOH is that Kurt immediately drops what he's doing and carves a swath through mobs and darkness to save Wolfie at all costs, despite having almost no torches, no food and no plan. The commentary makes this even better, as Kurt is clearly distraught at the thought of losing his companion and makes it clear he's willing to go to hell and back to save him.
What makes it even better is that Wolfie was in a forest, which Kurt HATES because of all the blind spots and ambush potential, yet he doesn't hesitate when he knows Wolfie needs him, and even makes the hidey hole there so he can make sure he doesn't lose Wolfie again.
A very morbid example occurs late in the F Lo B-athon, when Kurt contemplates killing himself to possibly bring Wolfie back. Normally, that would be reserved for a Tear Jerker, but the fact that Kurt is willing to risk absolutely everything to save his friend is heartwarming all the same.
Hearing Kurt change his tone about Wolfie over the course of the series. ("Wolfie, you idiot!" gradually turns into "Wolfie, are you okay?"). Particularly heartwarming because his first experience with the wolves in Far Lands or Bust was hilariously disastrous.
Far Lands or Bust: Episode 179. The title is Saving Wolfie, which is exactly what it sounds like. It works. Kurt is so happy he almost forgets to do his usual introduction.
His concern and extra-careful attitude around Wolfie the rest of the episode is heartwarming too.
Wolfie occasionally likes to follow Kurt into his end-of-episode hidey-holes.