A MILDURA martial arts expert forced to use his skills to save his dog from an aggressive kangaroo has joked that he may have invented "roo jitsu".

Mildura Martial Arts proprietor Mick Moloney was taking his three dogs for a walk by the Murray River when one of the pets, Hatchi, was grabbed and dragged under water by the muscular marsupial.

In footage originally posted to his Facebook page,...