Animal rights group, People for the Ethical Treatment of Animals (PETA), has written an open letter to Britney Spears's estranged husband Kevin Federline urging him to amend his custody application to include the couple's pets.

The letter cites PETA's long-held opposition to Britney Spears's treatment of her Yorkshire terrier, London, as an "accessory" and her notoriety amongst animal lovers who voted her "the overwhelming choice for Worst Celebrity dog owner"  in a 2006 poll.

PETA also alleges that Britney Spears was recently the subject of an investigation by the Los Angeles Society for the Protection of Animals following reports that she failed to obtain proper medical treatment for London after the dog's leg was fractured by being stepped on.

The well-being of the couple's children is at the heart of PETA's plea, with the letter making the case that "beloved companion animals can make a world of difference to the boys during this difficult time, and being separated from the animal friends whom they share a bond with is undoubtedly traumatic for them."