Cartoon series The Powerpuff Girls has featured a plot in which a transgender horse is convinced to transition to a unicorn – but becomes a monster instead.

The popular cartoon was recently revived by Cartoon Network – and an episode of its new run deals explicitly with trans issues.

In the episode, main character Bubbles encounters Donny, a talking horse who runs around with a fake horn on his head.

Donny explains: “I may not have a horn but I do have a heart, and in that heart I know I’m a beautiful unicorn!”

Bubbles convinces him to undergo a risky “transmogrifying” procedure to become a unicorn.

The horse agrees to the procedure without looking through the consequences – but it goes wrong and he turns into a giant monster.

Regretting the procedure, he complains: “Look at me! I’m a freak!”

Donny eventually finds a way to revert’ to his old self with help from the “Unicorn Coalition Alliance Brigade Headquarters”… and finds out he was a unicorn all along.

The episode ends with a heart in the shape of the trans pride flag – though some transgender people were left confused by the apparent anti-surgery slant of the cartoon.

Executive producer Nick Jennings told the LA Times: “Basically when it starts out, he’s a pony, but he wants to be a unicorn.

“He has to go through a transformation to become a unicorn and so it’s a whole [episode that asks], ‘What are you on the inside? What are you on the outside? How do you identify yourself? How do people see you?’ There’s a lot of subtext in that.”

“I don’t think you can be too young to start talking about those issues and thinking about those things and just presenting an attitude, and a voice that is going to resonate with people.”

The show’s villain ‘Him’ has long been portrayed as of ambiguous gender.

Click here to see 12 LGBT icons re-imagined as Powerpuff Girls.