How do I change the borders of the sprites?

[SerPase4kin]

Hey! Gentlemen and gentlewomen, I need your help! I wanted to make a mod for the siglplayer Dont Starve, the essence of which would be to add cat ears for Wheeler (yes...). But I came across the fact that the borders of the original sprites do not allow me to do this correctly. If someone knows how to change the boundaries of sprites, what is needed for this and what programs, I would be very grateful if you could help me figure it out!

P.S. I used a translator to write this message, so I hope you can understand me.