Flight delayed at SFO? The Wag Brigade is on the way.

(Left to right) LiLou, Jagger, Brixton, Toby and Benga! are part of the Wag Brigade at SFO airport. (Left to right) LiLou, Jagger, Brixton, Toby and Benga! are part of the Wag Brigade at SFO airport. Photo: Douglas Zimmerman/SFGate Photo: Douglas Zimmerman/SFGate Image 1 of / 50 Caption Close Flight delayed at SFO? The Wag Brigade is on the way. 1 / 50 Back to Gallery

Click through the gallery above to see the adorable animals of SFO's Wag Brigade.

Pure joy is not something you come across often in an airport.

Flights are delayed, security lines are long, and more often than not travelers are grumpy and stressed. But what if during the midst of a sullen march down a moving walkway, you met eyes with not another poor schmuck hauling an overstuffed carry-on, but instead, a fluffy golden retriever?

Enter the Wag Brigade, San Francisco International Airport's very own fleet of volunteer therapy dogs.

Whereas petting most dogs working at airports is strictly forbidden, members of the Wag Brigade wear blue vests that urge "pet me!" SFO has 22 dogs on the squad, plus the world's first-ever airport therapy pig (more on the pig later).

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Therapy dogs originated in the wake of 9/11 at the Mineta San Jose International Airport as a way to alleviate passengers' anxieties. A program at LAX called "PUP" launched in 2013; SFO quickly took notice.

"We launched as a pilot program in late 2013 with six dogs to gauge the reaction from passengers," said Jennifer Kazarian, an SFO employee who manages and trains the Wag Brigade. "The engagement was just amazing. So from then on we were like okay — send more dogs!"

All participating pets are graduates of the SF SPCA's Animal Assisted Interactions (AAI) training program. Becoming a therapy dog isn't easy — according to the SPCA, said Kazarian, "It takes a unicorn therapy dog to become an airport therapy dog because of the large crowds."

On a Tuesday afternoon, a few of these "unicorns" filed in for duty at SFO: Benga, a pekingese-shih tzu mix, Brixton, a golden retriever, and Jagger and Toby, both goldendoodles. Accompanied by their handlers, they went through security. Then, they headed to the Flight Information Display Screen to look for delays. Where delays are, stressed out passengers follow — and thus, the dogs are called to do their thing.

Usually, this means Terminal 3, where United Airlines flights are located.

Once the dogs parked themselves in the terminal, the crowds didn't take long to form. Young and old alike stopped in their tracks when they spotted the four friendly canine faces, gasping, giggling, or letting out quiet "aww"s. Some asked for pictures; others were satisfied with pets.

Each dog had a different approach: Brixton rolled onto his back to accept bellyrubs; Jagger excitedly wove through peoples' legs, his comically poofy hairdo delighting travelers; the owner of Benga, the smallest of the crew, encouraged passengers to hold her. When children approached the dogs, their handlers passed out trading cards featuring the dogs' faces and bios.

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"We often hear people say things like: 'I miss my dog more than my wife' or 'I just got back from a two-week vacation and this is the best part of my trip,'" recalled Kazarian.

But then, it was time for the real star of the show. A text announced her arrival: "The eagle has landed."

Minutes later, a pig with red-painted nails joined the dogs on the terminal. If people had been starting to lose it over the dogs, they were absolutely toast now.

LiLou, a whip-smart performer who lives in an apartment in Nob Hill, is the program's first certified therapy pig. Doing tricks such as twirling, playing a toy piano, and taking a bow, LiLou is obviously a huge hit whenever she makes an SFO appearance.

"Beauty, brains, and talent," announced owner Tatyana Danilov, fondly introducing LiLou to the now huge, mildly hysterical crowd forming in Terminal 3.

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Accepting attention and pets from a crowd of adoring fans seems like a pretty easy job, but it's not always a walk in the park for the Wag Brigade.

"An airport is a much more dynamic setting compared to other types of locations that animals and handlers might volunteer at," explained Kazarian. "Travelers may be experiencing a wide range of emotions, and Wag Brigade members need to be able to respond to this."

To combat this, animals undergo an airport familiarization experience before they start volunteering. They shadow a current therapy dog, learn about areas to avoid in the airport (i.e. the food court), and get a feel for whether the airport environment is a good fit for them.

But sometimes, meeting airport-goers on the less joyful side of the emotional spectrum is where the animals really shine. Linda Gordon, Brixton's owner, described instances of travelers heading to or from funerals, or of a woman who got stuck at SFO en route to Mexico petting Brixton for 30 minutes straight with tears streaming down her face.

"That helped get her through," Gordon recalled.

An hour and a half later, it was finally time for the animals to go home. It was difficult to get the crowd to disperse, as travelers kept approaching the squad for final pets. Really makes you wonder if people actually do miss their flights due to Wag Brigade sightings.

Madeline Wells is an SFGate editorial assistant. Email: madeline.wells@sfgate.com | Twitter: @madwells22