Dr. Anthony Pilny started the day shorthanded: A colleague at the Center for Avian and Exotic Medicine was bitten by an iguana while making her morning rounds.

An iguana's mouth contains about 100 tiny serrated teeth. The other vet, Dr. Jessica Grodio, went off to the urgent-care clinic to get stitches, leaving Pilny to do an enormously messy piece of gynecological surgery on a duck without an assisting doctor.

The duck was out cold on the table in a basement operating room, a breathing tube stuck down her bill. Pilny sliced open her abdominal cavity and rooted around.

"What is this?" he asked. "I'm seeing some sort of fluid-filled saclike structures. I see free egg yolk in her body."

There was little time to ponder the situation. On this Thursday morning not long ago, patients were stacked up in their cages: a guinea pig with hair loss, a rabbit unable to move its bowels, and the irascible iguana, now relaxing behind a sign that said "Use Caution Lunges." Others waited in recovery: a hedgehog newly minus one eyeball and a chinchilla who sacrificed a leg to the bars of her cage.

The center, on the Upper West Side of Manhattan, is New York City's only exclusively exotic animal hospital. "Exotic" in the veterinary trade simply means all pets except cats and dogs. The center treats anything else that comes in the door and weighs less than 50 pounds. Most of the patients are rabbits, rodents, lizards, or birds, but they can get pretty exotic: kinkajous, alligators, flowerhorn fish, and prairie dogs. So can their problems.

"I've been an avian and exotic vet since 2004," Pilny said, "and every day I say, 'What the hell is this?'"

Many of the center's patients are not legal in New York City, sometimes for good reason. "I'm not a big fan of people keeping a lot of the animals that come in here," Pilny said. But the center asks no questions and passes no judgments. It is not the pet police.

"We don't report anybody," Pilny said. "We just provide medical care."

Dino, the 3-year-old white duck on the operating table, was a longtime patient. In 2015, she lost her ability to form eggshells, and unlaid eggs built up inside her. Pilny removed most of her reproductive hardware but left her ovary because taking it out could make her bleed to death.

"Most birds, when you take out the reproductive tract, they stop ovulating," Pilny said. "This duck decided to break the rules."

Dino has other health issues. Her egg problems led to calcium deficiency, weak bones, and a fractured leg. She could no longer walk. "She can crawl around on towels, but otherwise we have to carry her everywhere," said her owner, E.J. Orbe, a ballroom dance instructor from Paterson, New Jersey.

Some people might hesitate to invest $1,200 in gynecological surgery on a lame duck. But Dino has a job: She's a seeing-eye duck for another of Orbe's ducks, Penguin, who is blind. "She finds food and water and makes noises, and Penguin would come over and start eating," Orbe said.

Inside Dino, Pilny was hacking his way through a sea of yolky blobs. "It's just a very extensive, severe amount of schmutz in here," he said to the veterinary technician, Kristine Castillo. A clamp on Dino's webbed foot fed her vital signs to a monitor. Her heartbeat pounded through the cheap speaker like a tom-tom drum: thwap-thwap, thwap-thwap.

The surgery ground into its second hour. The hospital's practice manager, Lorelei Tibbetts, poked her head into the small, beeping, thumping operating room. It was about Snorri, the constipated white rabbit. "He's looking at me miserably, like he has a balloon in his belly," she said. "Should we try laser?"

Pilny told her to hang on. A blood vessel burst. "That wasn't good," he said. He cut and sewed, cut and sewed. The bleeding stopped. Pilny decided he had done all he could for one day.

Pilny, 44, is one of three veterinarians at the center. He has a tattoo of a crane on one arm, a finch on the other, and a puffin on the back of his leg. He wears a tropical-theme surgical cap with parrots and green leaves on it. He is particularly fond of birds; he has 15 of them. He saves brightly colored feathers from his patients in a desk drawer in the hospital office and periodically sends them to the Pueblo of Zuni in New Mexico, where molted plumage is required for headdresses.

The center sees about 10 patients on a typical day. While there are no statistics on ownership of exotic pets in New York (especially illegal ones), Tibbetts said that more owners seemed to be seeking medical care.

"In the past, they were just considered 'caged pets' and most people didn't even consider taking them to the vet," she said. Most owners do not carry insurance, though it is available, Pilny said.

Pilny's next surgery was an ovariohysterectomy on a guinea pig. Her owners had brought her in because she was losing fur on her flanks. Pilny noticed that the fur loss was identical on both sides. Symmetrical alopecia is caused by a hormonal imbalance, which was probably in turn caused by ovarian cysts. Cut, snip, slice, sew, done. Fifteen minutes.

Tibbetts poked her head in again. "What did you find?" she asked.

"Nothing too exciting," Pilny said. "A little cyst on the left ovary, a little inflammation." He admired his handiwork.

"The thing that matters most to the owners is how they look when they pick them up from surgery," Pilny said. "No matter how lifesaving or complicated the surgery, what matters is when they pick the pet up and say, 'Look at that incision.'"

Pilny ate lunch at his desk. He called the duck's owner and told him the surgery had gone reasonably well.

"Maybe it buys her a good eight months or a year or something," he told Orbe. "I don't necessarily think she's cured, but I think this helped a lot."

After lunch, things got weird.

A rabbit was brought in for a dental issue, but during the exam, its eyes began jerking back and forth, a condition called nystagmus. Then it started running around in circles on the treatment table. "I told the owner it's either a bizarre coincidence or this is the real problem," Pilny said. The rabbit was tested and treated for a protozoan infection.

Meanwhile, the owners of Snorri the constipated rabbit came to visit him. While they were holding him, Snorri became agitated, moved his bowels violently, and collapsed. Pilny could not revive him.

Snorri's owners sobbed loudly behind a closed door, but the staff was a little shaken, too. Snorri had been born at the center six months ago. His parents were the pair of bunnies munching hay in the reception area. "It's a young rabbit," Pilny said. "It shouldn't happen."

By now, Pilny had a headache. The veterinary technician brought out the iguana. Her name was Spot. She was 9 and had a history of lesions and fungal infection. Her tail was amputated a while ago. Now she had a crusty lesion on the top of her head that needed to be biopsied.

The technician held Spot, tightly wrapped in a towel. Pilny gave her a shot of lidocaine. He took the tissue sample and then stuck a hemostat in the hole in her head to feel around. He expected to hit bone. He did not. "It feels like I'm passing it through beach sand," he said.

Pilny prospected a bit inside Spot's skull. Soon he had reached her sinus. Some blood came out of her nose. "I could dig around in here all day," Pilny said.

The grim jokes began to flow, like something out of M*A*S*H crossed with All Creatures Great and Small.

"Did she just blow air out of that hole?" Pilny asked. "Did I make a blowhole and turn it into a whale? I did — I turned an iguana into a whale."

Tibbetts came over to inspect. "This whole thing — it has no tail!" she said. "We had to chop its whole tail off. It's like rotting from the inside, and we can't stop it."

"That's like what the clients say: 'Is it rotting from the inside out?'" Pilny said.

"It is!" Tibbetts said. "This one the answer is yes."

Pilny wrapped Spot's toothy mouth shut with four layers of tape and took her off for an X-ray. It showed a large gap in the nasal bone. The sinus was filled with pus and exudates. The cause turned out to be a bone infection that required surgery and long-term treatment.

Spot's place on the prep-room table was quickly taken by the body of Snorri. Pilny had recommended a necropsy because the owners had two other rabbits.

Snorri's large intestine looked like an overinflated tire tube. Pilny explained that it had stopped moving food along, and the food had fermented and filled the intestine with gas.

"He got so severely bloated that the intestines leaked bacteria into the abdomen and he went into sepsis," Pilny said. A technician lit an odor-eliminating candle and laid it by Snorri's head.

Why Snorri's intestines stopped working was a mystery. Pilny took tissue samples to send to the lab. A custodian made a clay heart with Snorri's paw prints on it to give to his owners.

The day wound down. People came to pick up their pets. A tech brought up Elphaba the hedgehog, whose eye had to be removed after it became infected.

"Hi, beautiful," said her owner, Daniel Rodriguez. Elphaba wiggled her snout and sniffed enthusiastically. "Definitely better than yesterday," he said.

Then Spot's owner, Chris St. John, came to get her. St. John, an illustrator who lives in Manhattan's Hell's Kitchen neighborhood, conceded that she could be a handful.

"She's a tough one, and she can have a little bit of attitude, too," he said. "She can be a diva." Still, he said, he loved her very much.

Tibbetts brought up a taped-shut cardboard box and set it on the table. She showed the X-ray to St. John, pointing out the missing chunk of bone: "And these are her teeth, which found their way into Dr. Grodio's finger today."

"Oh, I'm sorry," St. John said.

"It's all right," Tibbetts said with a laugh.

St. John unboxed his iguana. "Baby," he said softly as she extended her long green legs. He caressed her dewlap.

"Hey, cutie patoots!" Tibbetts said brightly. Tibbetts told St. John to get Spot eating again. "I'm worried about her weight loss."

"I'll do it," St. John said. "She's been through a..." his voice faltered.

"Been through a lot," Tibbetts said.

St. John kissed Spot's spiny back. "OK, girl," he said, "you're heading home."

Excerpted from an article that originally appeared in The New York Times. Reprinted with permission.