The multibillion fortune of New York’s “Queen of Mean” could be going to the dogs.

A newly disclosed document shows that the hotel tycoon Leona Helmsley left instructions before her death last year at the age of 87 that almost all of her huge estate should go to the care of dogs.

The bequest could provide a windfall of up to $8 billion (£4 billion) for animal care charities.

The gift would dwarf the $300 million Maddie’s Fund, set up by the PeopleSoft founder David Duffield and his wife in honour of their miniature schnauzer.

“This is the largest potential donation – or investment – in the cause of animal welfare,” said Wayne Pacelle, president and chief executive of the Humane Society.

The Helmsley bequest could fund more dog shelters for unwanted strays, he said. “It has the potential to eliminate the euthanasia of millions of dogs. It can help us to shut down 10,000 ‘puppy mills’ – large-scale commercial dog breeding operations where dogs are treated like a cash crop.”

But lawyers say that the trustees of Mrs Helmsley’s charitable trust – set up to distribute her fortune after her death – have the discretion to spend the money elsewhere.

Mrs Helmsley, the widow of the tycoon Harry Helmsley, owned the Helmsley hotel chain and a property portfolio that included a stake in the Empire State Building. She gained notoriety when she was jailed for 18 months for tax evasion in 1989 after declaring: “Only the little people pay taxes.”

Her will made headlines when she left $12 million to her white Maltese bitch Trouble , who was spoon-fed gourmet food by maids at her 46th-floor flat in the Park Lane Hotel in Manhattan.

The dog was forced to go into hiding in Florida after receiving dozens of death threats, fleeing on board a private jet with a team of security guards. She is now living with Carl Lekic, the general manager of the Helmsley Sandcastle Hotel in Sarasota, Florida.

Last month a judge cut Trouble’s inheritance to $2 million and awarded $6 million each to Mrs Helmsley’s two disinherited grandchildren.

Mr Lekic said $2 million was plenty to keep Trouble in the lap of luxury: “Two million dollars . . . would be enough money to pay for Trouble’s maintenance and welfare at the highest standards of care for more than ten years, which is more than twice her reasonably anticipated life expectancy.” He put Trouble’s annual expenses at $190,000, including $100,000 for round-the-clock security, $60,000 for his guardianship fee, $8,000 for grooming and $1,200 for food.

Now, details have emerged of a two-page “mission statement” accompanying Mrs Helmsley’s will in which she directed that her entire charitable trust be devoted to the care and welfare of dogs. The New York Times reported that Mrs Helmsley signed the mission statement in 2003 to establish the goals for the multibillion-dollar trust. Originally, she set the two goals as helping destitute people and providing for the welfare of dogs, but she later deleted the first goal.

Lawyers suggest, however, that the trustees may not be bound by Mrs Helmsley’s wish. The mission statement was not incorporated into the will or the trust documents, they point out, and it allows the trustees discretion in distributing the money.

Mrs Helsmley had $2.3 billion in liquid assets at the time of her death, but her property assets are expected to yield another $3 billion to $6 billion.

The disposal of her property empire is being handled by the five executors of her will – her brother Alvin Rosenthal; two grandsons, Walter and David Panzirer; her lawyer, Sandor Frankel; and her friend, John Codey.

The five are also the trustees of the Leona M. and Harry B. Helmsley Charitable Trust and are said to be concerned about the public reaction to the trust’s terms.

They could donate to animal shelters or groups such as the American Society for the Prevention of Cruelty to Animals or the Humane Society that routinely help dogs.

But they could also distribute funds to veterinary schools or research into canine diseases.

“We are concerned that some people may attempt to divert funds from the stated purpose,” Mr Pacelle said.

“We think that Ms Helmsley should be able to do what she wants with the money.”

$8bn would buy . . .

400,000 canine open-heart surgeries

800 million cans of food

100 million six-month courses of worm and flea treatment

1.6 billion squeaky toys

It could also provide for 427,350 dogs for their entire lives

The Times