Much of the world comes to a happy halt on Christmas morning, but snow still must be cleared, chocolate-snarfing dogs need emergency care, fires break out, and motorists get in accidents.
So a small cadre of people is on the job on a day when streets are empty and ghostly quiet, and nearly all businesses are shuttered.
"It's a blessing that this place is open today," Mike Stragand, of Pine, said of an emergency veterinary clinic in Ohio Township. He had brought Gracie, his miniature long-haired dachshund, to the Pittsburgh Veterinary Specialty and Emergency Center several hours earlier on Christmas Day.
Gracie, who is 12, was suffering from a dental abscess that had spread to one of her sinuses. She was one of more than a dozen animals that were seen and treated before 1 p.m. by the emergency vets and technicians on holiday duty.
Following her examination and treatment with antibiotics, Gracie would be going home with Mr. Stragand.
Christmas can be hazardous to pet health and the center is well-staffed in anticipation of holiday mishaps. Cats are partial to ingesting tinsel and ribbon, while dogs will eat almost anything, explained Dr. Kenton D. Rexford, owner of the veterinary emergency center. He recalled one case involving a pooch who ate both a holiday pie and pieces of the broken plate in which it had been baked.
"When we interview someone for a job, we explain that we are open 365 days a year," said Dr. Rexford. "That means regularly working weekends and holidays."
He has worked 12 of the last 13 Christmases, including this year's.
Like Dr. Rexford, some people know they'll work many holidays by virtue of their chosen profession: firefighters, snowplow drivers, newspaper reporters. Some choose to work to free others to be with their families.
Paul Dion, assistant facilities manager at the Carnegie Science Center, left his five children at home Saturday morning in order to go to work. He cleared science center sidewalks -- in order to comply with the city's snow removal ordinance -- so that one of his staff members wouldn't have to.
The overnight snowfall meant the Pennsylvania Department of Transportation had to beef up its normally lean holiday crew. Leo Rauterkus, who has worked for PennDOT for 31 years, spent nine hours of his Christmas behind the wheel of a snowplow. He was scheduled to return at midnight.
For firefighters, Christmas at the firehouse is familiar. Firefighter Walter Haig, a 21-year veteran, has spent many holidays away from home. He was at Engine Co. 37 in Manchester Saturday morning, when there were no calls, giving him a quiet Christmas morning.
Not so at the Allegheny General Hospital emergency department, where patients filled 26 of the beds by mid-afternoon with ailments ranging from nausea and swollen fingers to heart attacks and strokes.
The holidays tend to bring more people with gastrointestinal ailments from overconsumption and more strained backs with the less limber hauling Christmas trees and scaling slippery ladders to put up lights. But because people with sore throats and sniffly noses tend to tough it out on the 25th, a higher proportion of cases are more acute, according to those who work there. This, and the mere fact that it's Christmas, can make the work doubly hard for the staff.
"It's supposed to be the holidays, where people are happy," said Dr. Fred Harchelroad, chairman of the department of emergency medicine. "But there are [patients] who are not going to make it. It can be emotionally draining."
He said that at the end of the day, he's happy he gets to go home to his own family.
Dr. Michael Yeh, a resident, said that the holidays can be especially difficult for patients who have an expectation that they'll spend it with their families. Earlier in the day, he treated a woman who thought she had indigestion. It turned out she was having a heart attack, and she'd have to spend the day in the hospital. She was upset because she was going to miss Christmas dinner with her family.
"It always comes as a shock, especially when it's a special day and people have big plans," he said.
Mike Abbitt, a Pittsburgh paramedic, said Christmas can be a lot like other days on the job: unpredictable. But there is one thing he said he sees more of during the holidays -- calls from people in need of company rather than medical attention.
One year on Christmas he responded to a 911 call from an elderly woman seeking medical help and arrived to find her healthy. But she was spending Christmas by herself.
"She had no health problems. It turns out she was lonely," he said. "She had a big family. But they ignored her."
So he cooked her breakfast, made her some tea and talked to her for a while before heading out again.
"It really made my Christmas being able to help someone like that," he said.
It's not as if the holiday went unnoticed at AGH. Staff members donned Christmas-themed scrubs, and behind a locked door in a break room there was a full potluck spread: bubbling slow cookers, buffalo cheese dip, crackers, sweets and salami. Jerry Wasek, a towering paramedic with a shaved head, donned a fuzzy Santa hat, which he said made some of his patients laugh.
Some coped by finding family within the hospital walls. Dr. Morgan Garvin, a first-year resident, is a long way from home -- her family is in Medford, Ore. -- and she said this is the first year she won't see them for the holidays.
"I feel like my residency family counts," she said. "So I do get to see my family, so to speak."
At the animal ER in Ohio Township, meanwhile, there appeared to be plenty to do for the five veterinarians, 13 technicians and three receptionists working their normal 12-hour shifts on Christmas Day.
Shelly Chesner, of Munhall, has worked at the emergency center for nine years. She said her two daughters, now ages 8 and 11, don't think twice about her having to work on holidays.
"I like the pace," she said of emergency clinic work. "There's always something new and you learn quickly."
There certainly was something new Saturday afternoon.
Technicians brought in a wounded ball python with several large bites visible along its long slender body. According to its owner, the snake had been attacked and injured by what was meant to be its Christmas meal: a live rat.