Ferrets, the weasel-like rodents that have recently become popular as pets, cannot be effectively vaccinated for rabies and will viciously attack infants without provocation, two doctors warned last week.

Drs. John Paisley and Brian Lauer, writing in the Journal of the American Medical Association, cited three recent attacks and the rabies risk in calling for state restrictions on the sale of the animals.

"I don't want to come off sounding like a ferret hater, though I certainly don't love the animals," Paisley said. "Some people think they're really wonderful pets, but we wanted them to be aware of their feisty and sometimes vicious behavior."

The Anti-Cruelty Society shared the doctors' view.

"We don't adopt ferrets and we don't recommend people keep them as pets," said Jane Alvaro, a society spokeswoman. "They are not trainable animals, they do have a horrible odor and it's really not possible to housebreak them.

"Plus, they're mean, vicious little animals," she said.

Nevertheless, the popularity of pet ferrets is soaring, with an estimated 1 million now in homes and 50,000 sold annually. Despite the fact they are still considered wild animals by the national Centers for Disease Control, ferret lovers claim they are quite gentle, Paisley said.

Paisley, a pediatrician at Denver General Hospital, said only a small number of ferret bites have been reported because most state agencies do not require them to be, as they would do with dog bites. Ferrets also tend to bite their owners, who are unlikely to report it, he said.

In the journal, Paisley and Lauer reviewed three particularly vicious ferret attacks on infants:

In Colorado, a 4-month-old girl was attacked by her babysitter's pet ferret shortly after finishing a bottle. The wounds to her face required 39 sutures.

Also in Colorado, a 3-month-old girl, drinking her bottle in her crib, was attacked by a ferret her father had found wandering the streets two weeks before. About 40 percent of both of her ears were chewed off, requiring plastic surgery.

In North Carolina, a 6-week-old boy was attacked by the family's ferret in his crib. Most of the boy's left ear was chewed off.

Paisley speculated that ferrets may attack babies on instinct, drawn to the smell of milk. In the wild, ferrets are known for preying on suckling animals.

Although rabies is rare in pet ferrets -- only five rabid pets have been reported since 1980 -- there is no effective rabies vaccine for the animals and the only way to know if the animal is a carrier is to kill it and examine its brain, Paisley said.

California, Georgia, New Hampshire, New York City and Washington, D.C., have all prohibited the sale of ferrets as pets, Paisley said. But he added that in some areas, ferret owners are organizing to defend the rodents.