Just a heads up: seems like this only runs with Java 8, or at least it wouldn't start with my default Java 17.
Lovely palette and overall feeling, and very pretty music. Feels more like a puzzle game than a platformer, too (which is fine by me!), though the springs launch you fast enough that sometimes the execution is tricky.
Love having a bark button. I use it all the time even when I don't need it :)
Very charming, well done! I think my only real critique would be that, generally, pixel art games try to keep all the pixels the same size :)