Tammy Darke visits Heather Dean with her three-year-old Weimaraner, Colt, at St. Mary Medical Center in Long Beach, Calif., on December 5, 2012. ( Jeff Gritchen / Staff Photographer)

Colt is a ham.

The 4-year-old Weimaraner instinctively mugs for cameras, freezing when someone aims a lens in an attempt to capture the canine making its way down the halls of St. Mary Medical Center in Long Beach with a human companion, Tammy Darke.

At least once a week - year-round - Darke, a dietician, escorts Colt or one of two 6-year-old Weimaraner siblings during surprise visits that brighten up stays of patients and the routines of nurses, doctors and technicians.

The visits these days are generally eye-openers, since the dogs dress as Santa Claus, white beard and all.

"Wow! Look who's here," shouted Gilbert Murillo, a cancer patient and grandfather who was surrounded by many members of his

Gilbert Murillo breaks down in tears as Tammy Darke visits with her three-year-old Weimaraner, Colt, at St. Mary Medical Center in Long Beach, Calif., on December 5, 2012. (Jeff Gritchen / Staff Photographer)

Patient Heather Dean, a dog owner, enjoyed petting Colt's grey velvetlike coat. Mamie White shared her hospital bed with Colt, as the dog took a brief recess from walking the hallways.

Everyone was given plenty of opportunities to hug the canine Claus, while Darke looked on like a proud parent.

Darke works for the hospital's Comprehensive AIDS Resource Education program and clinic, but she's also a volunteer who delivers canine cheer.

"It's always something I wanted to do," said the 43-year-old Cal State Long Beach graduate, reflecting on her volunteer work. "I think animals can make a big difference, because hospitals are sterile, unhappy places."

Darke got the nod from her boss to use the dogs about 18 months ago. She then got the pets formal training and had them registered with Pet Partners for patient therapy work.

Pet Partners' national therapy animal program trains volunteers and screens them and their pets for visiting-animal programs in hospitals, nursing homes, rehabilitation centers, schools and other facilities.

The dogs are given training in basic obedience, and they are screened for the right type of

They also can't respond negatively to people of color or to different genders.

"They have to be acclimated to all of that," Darke said.

"Not every dog is born to do it," she added. "But my dogs are very good with people; they have unique personalities."

One of the Weimaraners, Joey, is athletic and has a happy, silly personality.

"People like that," Darke said. "They ask for him."

On the other hand, Joey's sister, Molly, is quiet and likes to sit near people.

"She's very calm," the dietician said. "Joe is the opposite, and he nudges his nose into people."

Colt, meanwhile, is strong, calm and rarely excitable.

Darke said patients enjoy all of the personalities.

"But people respond better to one or the other," she added.

Sometimes, people at the hospital don't respond well to any of the dogs.

Even if a dog is in costume, some people get uneasy when they see the pet walking down the hallway.

"I watch people," Darke said, adding that she takes action to ease the person's uneasiness. "I switch sides with the dog."

Before getting on an elevator, Darke asks the passengers if the dog would cause uneasiness. If so, the volunteer takes another elevator.

"I try to be considerate," Darke said. "I don't want people to be trapped in an elevator."

While the dogs are popular with most patients, it turns out they have also become popular among staff members, who often whip out smartphones to take photos.

"The dogs' visit is as much for the patients as for the staff," Darke said.

joe.segura@presstelegram.com, 562-714-2167, twitter.com/JoeSeguraPT