He arrived as the ultimate designer pet, miniscule enough to fit in a teacup.

Pigwig, the so-called ‘micro pig’, couldn’t get any cuter as he slept snuggled up in a blanket and was tinier than a terrier.

But today he’s nearly five and he’s an uncontrollable 20 stone porker who leaves a trail of destruction in his wake.

His owners Margaret Smith and her daughter Emma are among many across the country who became enchanted by the tiny pigs.

They followed in the footsteps of stars Paris Hilton and Jonathan Ross to part with as much as £1,200 for the promise of pint-sized pets that would grow no bigger than 12 inches high.

But they might have been told a porkie.

The RSPCA say there is no such thing as a micro pig.

Instead the hogs are bred by selective breeding where ordinary pigs are bred generation by generation, selecting the smallest each time, a process which often involves inbreeding that has associated welfare problems including decreased fertility and increased risk of deformities.

“Although these pigs are advertised as being ‘micro’, people might not be getting what they think they are expecting.

“Some so-called micro pigs may grow to be much larger than expected by the time they reach adult size,” an RSPCA spokesman says.

Pigwig is typical of many adult micro pigs across the country – and there’s nothing micro about him.

Luckily Pigwig’s owners have space in their Ringwood garden, where the swine lives.

But those people unaware of just how big they get and unable to cope with the full-sized farm animals in their homes have been forced to abandon them.

“A lot of them have gone to slaughter and some people are dumping them,” says Margaret, who has set up an internet site for people in a similar situation.

And the local grandma isn’t alone.

There are 122 members including one woman from Salisbury whose life has been taken over by a pair of ‘micro pigs’.

They have trashed her tiny semi-detached home by ripping up the wooden flooring, eating the bottom two stairs and urinating on the furniture to mark their territory.

Emma, 29, explains: “There are two girls living together and one of the female pigs got territorial over one of the girls so when she came home from work, it wouldn’t let her in the house without the other being there first.

“She had to wait outside the house before she could even enter because the pig wanted to eat her!”

Emma says there is also a family in London with five children who joined the site after their boar began attacking the children.

There are regularly posts from people desperately looking for homes for their pigs.

“The options are slim,” Margaret, 68, explains as we’re out in the garden with Pigwig who is incessantly squealing and grunting.

“You might find someone to rehome a cat or a dog but rehoming a full-sized pig is slightly more difficult.”

Like many of the owners, Margaret and Emma were ecstatic when they first got the ‘micro pig’ and were told he could live in the house.

Emma, who runs Eksclusive Designs Couture Dressmaking, says: “He was only as big as a chick when we bought him.

“I used to carry him around the house wrapped up in a blanket like a baby.

“We thought that’s what he would have been like, just like a pet.

“But he kept growing and growing. Soon we couldn’t keep him inside anymore.”

Pigwig charged through a baby gate in the house which Margaret had to replace with a stable door and he tore apart the sofa and pulled a radiator off the wall.

Even outside he ripped up the garden lawn as he foraged for food.

They were forced to buy another pig Percy, a kune kune pig, which are smaller than average pigs because Pigwig became lonely.

And they have spent thousands of pounds making a pig-proof pen in their back garden.

“It’s cost us an awful lot of money. He grew and grew and grew.

“It all looks very glamorous in the marketing but it is not glamorous at all.

“He has transformed into a big boisterous pig. I know for a fact he could take a human out,” says Emma, who was once attacked by Pigwig leaving her with a huge bruise on her leg.

Margaret got the £450 she paid for Pigwig back after she complained to the breeder, who has now closed her business (he’s actually just a Large Black – a breed of pig worth £25 from a farmer’s market).

She says: “Most of them have shut down.

“Our online group tries to get the truth out there so these places close.

“People need to know how they turn out after several years.”

Their advice for people looking at buying a ‘micro pig’ is simple.

“One hundred per cent don’t get one.

“There is no such thing as a micro pig.”

Paris Hilton started it all off with a pig in her handbag but there’s no such thing.

“You never see a fully grown adult micro pig. We have asked and asked, ‘can someone show us a fully grown micro pig?’ If there is a fully grown adult pig that’s tiny we’d like to see it.

“But we think we will be waiting a very long time. Pigs might fly.”