By Manny Fernandez for The New York Times

Tyson was a tough-looking, head-turning dog — a 60-pound, year-old Staffordshire bull terrier with a silver-gray coat and blue eyes. But the only thing tough about him was his name, his owner said.

Tyson followed commands, never bit anyone and liked to put his paws on people’s heads to play with their hair. “He was a big baby,” said his owner, Marc Hernandez, 20, who had had Tyson since he was a puppy of 7 weeks.

Yet one day in May, Mr. Hernandez, a student at John Jay College of Criminal Justice, took Tyson to an East Harlem animal shelter, where he reluctantly and tearfully surrendered him. The problem was not Tyson’s behavior, but his home: Mr. Hernandez lives in one of New York City’s public housing projects, where a ban on pit bulls and other large dogs went into effect May 1.

Kanielle Hernandez, of Manhattan, has refused to give up Denim, a 60-pound pit bull, and says he is well behaved.

The ban, one of the strictest for any public housing authority in the country, prohibits residents from keeping pure-bred or mixed-breed pit bulls, Rottweilers and Doberman pinschers, as well as any dog, with the exception of service dogs, expected to weigh more than 25 pounds when grown.

It has divided tenants and outraged animal welfare groups.

For the New York City Housing Authority, keeping track of the pets in 178,000 apartments has been a challenge. But the way the agency announced the policy and the way it has enforced it has confused and angered many.

Under the 14-page policy, residents who already owned dogs on the outlawed list could keep them if they were registered by May 1, but many tenants failed to do so and were forced, like Mr. Hernandez, to choose between keeping their dogs or their apartments.

Since April, the owners of at least 113 dogs have given them up, citing the ban, to shelters and centers run by Animal Care and Control of New York City, the nonprofit group that has a contract with the city to take in unwanted animals.

Of the 113 dogs, 49 have been euthanized, because of illness, behavior or a lack of space. Fifty-nine were adopted by individuals or taken by rescue groups, two remain in shelters and three were reclaimed by their owners.

The statistics were supplied by the Mayor’s Alliance for NYC’s Animals, a coalition of animal rescue groups and shelters that examined shelter intake records.

The Mayor’s Alliance, which is not affiliated with the mayor’s office, and the American Society for the Prevention of Cruelty to Animals have asked the Housing Authority to stop enforcing the ban. The groups found that many of the dogs turned in were described as well behaved by shelter workers.

“You can’t predict what a dog is going to be like just simply based on its breed,” said Jane Hoffman, president of the Mayor’s Alliance. “I don’t want a dangerous dog out there. But doing it this way is wrong and it’s condemning perfectly innocent dogs to death.”

City Councilwoman Rosie Mendez of Manhattan, the chairwoman of the Council’s Subcommittee on Public Housing, has also called for a re-examination of the policy. She said one resident with a 28-pound poodle told her that she planned not to feed the dog until it was under the 25-pound limit.

A spokesman for the Housing Authority, Howard Marder, said the new rules were a response to complaints and reports of dangerous and threatening dogs from tenants, tenant leaders and the police. The three breeds on the forbidden list had been identified as “the most frequent problem breeds,” Mr. Marder said.

There have been several attacks by pit bulls in public housing buildings in recent years. A 12-year-old girl was mauled by two pit bulls in Brooklyn in 1997, and there have been more than 17 dog attacks since 2007 in which people were hurt or other pets were killed or maimed.

Mr. Marder said that the Housing Authority had discussed the issue with animal welfare groups, but that he was not aware of any plans to ease the restrictions. “We made these changes based on the realities of what we hear from residents living in public housing, about how difficult their lives are because of being threatened or attacked by these animals,” he said.

Victor A. Gonzalez, 60, tenant association president at Rabbi Stephen Wise Towers on the Upper West Side, said he knew of about 16 pit bulls there. “The elderly are fearful,” he said. “They’re afraid to get on the elevators with these dogs, much less be in the lobby when they get in.”

As of July 31, there were 4,792 dogs registered with the authority. So far, no one has been evicted for having an unauthorized dog, but the authority has pursued 41 termination-of-tenancy cases against residents for violating the pet policy. Nine cases have been resolved, Mr. Marder said: Some were withdrawn at the housing manager’s request and one tenant gave a dog to a friend. The 32 others are pending.

The agency announced the rules by publishing a notice in the April issue of its monthly newspaper. But that notice listed 27 prohibited breeds, including the Shar-Pei, the cane corso and the dogo Argentino. Mr. Marder said the agency had tried to identify breeds that exceed 25 pounds when grown, but realized that the long list was “impractical” and cut it to three.

Tenants have received verbal and written warnings about their dogs from housing managers. An employee instruction guide on using the agency’s computerized program of pet tracking is 37 pages long, and maintenance workers who go into apartments to make repairs make a note of any pets in the household, Mr. Marder said.

Mr. Hernandez, who lives with his mother at Mariana Bracetti Plaza in the East Village, took Tyson into the management office the day before the ban started, but Tyson could not be registered because he also exceeded the previous weight limit, infrequently enforced, of 40 pounds.

Mr. Hernandez said he feared that he and his mother would be evicted if he kept Tyson. “I got scared, so of course I’m going to do it,” he said. Mr. Hernandez later learned that Tyson had been adopted.

Kanielle Hernandez, 23, who lives in the same building as Mr. Hernandez but is not related to him, refused to give up Denim, her 60-pound blue-nosed pit bull, after he was refused registration because of his weight.

She said she walked Denim when housing managers were not around, as if harboring a fugitive. “I’m still cautious,” she said. “I get scared if I see a manager.”