Michael Jackson and Mike Tyson each have one; the magicians Siegfried and Roy are known for their specially bred white tigers in Las Vegas; the internet and specialist trade magazines advertise exotic-animal auctions and 'jungle-cat reduction sales'. The National Alternative Pet Association — 'Do people put you down because your pet isn't a socially acceptable cat, dog or goldfish?' — promotes ownership of endangered species. Prices are not particularly prohibitive: $1,000 for a generic cub, $3,500 for a pair of Bengal tigers, then rising to $15,000 for a more fashionable white tiger.

The private trade originated in zoos. Tiger cubs proved so popular with the public that zoos started breeding more than they needed and sold the surplus to private breeders. The US Endangered Species Act of 1973 outlaws the taking of endangered animals from the wild, but does not regulate what happens to the offspring of animals captured before the law was passed.

Today in Texas there are said to be 4,000 pet tigers, more perhaps than the number that roam free in India, and because captive tigers are just as fertile as domestic cats, the numbers are likely to grow. Some private owners simply like being different, while others find the sleek feline almost erotically intoxicating. There are even stories of tigers being used as 'guard cats' by drug dealers.

Many owners believe they are saving an endangered species. But their cubs have no equivalent among wild tigers. They are generic, a mixture of, say, Sumatran, Siberian and Bengal tigers, which would not survive in the wild.

Conservationists are also worried at the level of inbreeding. There are so few regulations regarding the trade of tigers that records of a big cat's origin are few. And because of the relatively low numbers available, the gene pool is impoverished and blindness and kidney problems are increasingly common.

More immediately, the owner is responsible for a carnivorous predator. The kitten-for-Christmas syndrome is magnified when applied to tigers: the cartoon-cute cub can transmogrify within 15 months into a 180-kilogram eating machine capable of devouring £130 worth of meat every week. As a result, former pets are beginning to fill up animal sanctuaries across the US, and zoos say they already have more than they can take. Unwanted tigers are found chained in basements, starved in makeshift back-yard cages, or wandering the streets after being set loose by bored, frightened or broke owners. Some arrive in sanctuaries with mutilated paws - the result of attempts at de-clawing them with garden shears. Occasionally, surplus tigers are killed for their skin, more valuable than the animal. Others become the quarry in 'canned hunts': for a fee of up to $20,000 (nearly £13,000), a wannabe big-game hunter can bag a caged tiger.Concern is also growing about the number of tiger attacks on people.

In October 2001, a three-year-old boy was killed in Texas by his grandfather's tiger. The year before, a four-year-old put his arm through the bars of a cage housing a Bengal tiger kept as a pet by his uncle; his arm was torn off. The Humane Society of the United States has compiled a list of three dozen such attacks in the past 12 years. At least seven people have been killed by tigers in the US in the past four years.

The problem for those who want to see further regulation of the keeping of dangerous pets is that legislation varies from state to state, even from county to county. Many owners also claim they are 'licensed exhibitors', thereby escaping any restrictions; enforcement is often lax.

At present, 19 states ban or severely restrict tigers as pets; the rest require permits or have minimal restrictions. In January a bill was introduced in the Senate to make it a crime to sell exotic wild cats across state lines. If passed, it would be the first federal regulation of pet tigers. But even if public safety improves and ill-treated cubs are protected, the question remains: what will the authorities do with them all?

[Photographs by Sam Faulkner accompany this article in the newsprint version of The Sunday Times Magazine]