Katy Perry and Russell Brand have bought a cat together.

The animal-loving couple already have two feline pets between them but have added a third to their menagerie, who they have called Krusty, an amalgamation of the 'I Kissed a Girl' star's first name and the comic's nickname Rusty.

It was recently claimed that Russell had sought out a therapist to treat his cat, Morrissey, after the animal started behaving strangely.

A source said: "Morrissey keeps weeing all over the house and scratching everything. He's gone bonkers."

The 'Get Him To The Greek' star was left amused when the animal behaviour specialist told him his pet was acting out of character because he was jealous of his relationship with Katy, whose own cat is called Kitty Purry.

The source added: "He thought it hilarious. Only he could have a cat fighting for his attention."