PET owners in Britain are creating a nation of lonely, overweight and badly-behaved animals.

The claim comes from an international pet help centre which says that the number of calls from owners worried about their animals has shot up by 30pc.

Now model and animal lover Heather Mills has lent her weight to a campaign to help promote better pet ownership in towns like Bolton around the UK.

"I think that having a pet is as big a responsibility as having a child," said Heather, who has a dog called Oliver. "And more people need to recognise these responsibilities."

Heather, aged 32, is backing the team at PetMad -- the first on-line, one-stop shop for pet lovers to offer free advice from a team of zoologists, vets and veterinary nurses.

The service says that its calls suggest that more than 40pc of the nation's pets areoverweight.

"This free PetMad.com service will be a particularly useful way to get advice for those with disabilities or living in the countryside," said Heather.

As nearly half of the 24 million households in Britain own an animal, PetMad claims that we are leaving almost 17 million pets home alone for long periods every day. This can lead to attention-seeking problem pets once people get home.

They want owners to think about their pets as animals rather than "little people".

As resident veterinary nurse Olga Gibbs says: "We're prone to treat our pets as one of the family, but we're spoiling them with rich titbits from the table, and it's often out of guilt because our busy lifestyles mean we're leaving them home alone more often.

"This also means we're not exercising them enouth either -- so it's not surprisng that a bored, lonely and restless animal is going to play up." And while TV shows like Animal Hospital tug on the heartstrings and raise the profile of animal care nationally, these experts say that they are "also helping to create pampered, overweight pets that are running rings around their owners like never before".

Olga Gibbs added: "Rolf Harris and his team are great in educating viewers about how to look after their pets, but the 'aah' factor is also making us spoil our own pets once the show is over."

The new service features a wealth of advice to keep owners on the straight and narrow, including information on feeding animals a healthy diet and the need for suitable exercise. It also urges owners to spend time with their pets.

"Animals need a consistent diet which is suitable for their breed," said Olga Gibbs. "And exercising your pet doesn't mean you have to go on a four-hour hike every morning -- 20 minutes playing with a ball or letting caged animals have a run around your kitchen is fine.

"It also ensures that you're spending quality time with a pet, which is important if they're being left alone all day whilst the family is at school or at work."