A FAT cat called Cookie will be cutting down on tasty treats in a bid to win a pet fit club competition.

The 15-year-old is among more than 18m dogs, cats and rabbits which are fed potentially life-threatening meals which can lead to arthritis, diabetes and heart disease, veterinary charity PDSA has found.

At 18.5lbs Cookie is as heavy as an average seven-month-old baby and weighs twice as much as a healthy cat should.

The elderly feline was brought to Middlesbrough PDSA Pet Aid Hospital at the beginning of March by her concerned owners suffering from arthritis and other age-related ailments which prevented her from exercising and burning off calories.

Now Cookie's health issues are being treated she will be weaned onto a diet, said head nurse, Stephanie Williams.

“The owners’ granddaughter said, “she is a bit of a cookie monster, isn’t she?” The attitude often is, 'if I’m having a treat they should have a treat’ but it becomes a habit. Middle age spread applies to pets as well as people.”

Dr Alex German, an animal obesity specialist at the University of Liverpool’s veterinary school, said pet obesity was entirely preventable and could be reversed with veterinary supervision and owner dedication.

PDSA has now launched its annual animal slimming competition to find Britain’s fattest pets and help them get fit over six months. Owners can enter their pets at www.pdsa.org.uk/petfitclub. Entries close on Friday, April 12.