In the Teenage Mutant Ninja Turtles (2012) episode " Mikey Gets Shellacne ," Michelangelo develops a dangerous, mutating skin condition after consuming experimental, tainted mutagen. While his brothers rush to find a cure at an abandoned lab, they battle the newly transformed Rahzar, a deadly, canine-like creature created by a second mutation event. The episode concludes with a frantic fight for the antidote, resulting in a cured, yet still teased, Michelangelo.
You can watch this episode and the transformation of Rahzar on YouTube or stream it through Apple TV . Mikey Gets Shellacne - Teenage Mutant Ninja Turtles [S2E5] Mikey Gets Shellacne