Cat owners are being urged to vaccinate their pets against a rare and potentially deadly virus outbreak in Melbourne.

The highly-contagious feline panleukopenia virus, commonly referred to as feline distemper, has been confirmed in a handful of stray kittens, and the RSPCA is urging cat owners to keep their pets' vaccinations up to date.

"The virus is not contagious to humans or any other animals, however, it can be spread to other cats through the clothing and shoes of handlers or owners of infected animals," RSPCA Victoria said in a statement on Sunday.