Ryder means the world to Shamus Butler.

“He’s my best friend, my companion, my partner, my son, my brother,” Butler said about his dog. “He’s everything to me, and I want to make sure that he’s taken care of before anything. He gives my life purpose.”

Butler, 28, has been homeless for about eight years. Wanderlust keeps him on the move around the country and so does following the Grateful Dead spinoff band Dead & Company. He adopted Ryder as a puppy nine months ago after the band’s concert in Denver, and the two have been inseparable since.

On a recent Saturday morning, Butler spotted a banner for the group Street Dog Coalition outside the Episcopal Diocese of San Diego in Ocean Beach. Inside the courtyard, he found a table with bags of dog treats, food and pet jackets. There was also a team of veterinarians and volunteers ready to give exams, vaccinations and medication to prevent animals from getting fleas and ticks.

“I really appreciate it,” he told the veterinarians after they administered medication for Ryder’s cough, checked him for heart worms and gave him a handmade soft jacket. “You guys did a whole lot more than I expected.”

Veterinarian Jon Geller started the coalition in 2015 to help homeless pet owners he saw around his practice in Fort Collins, Colo. Other veterinarians quickly joined him.

“The reason it’s expanded so much is that veterinarians are saying, ‘We want to do this,’ ” he said. “It’s taken on a life of its own.”

The coalition has expanded to more than 20 states.

Not all volunteers are veterinarians. Pam Yarberry, a dental assistant, helps with administrative work and coordinating supplies at the clinics.

“The most impressive thing to me is the bond that they have with their pets,” she said about meeting homeless people at the clinics. “Their pets mean absolutely everything to them, and they’d give up anything to be able to keep them. A lot of them have actually lost their homes because they wouldn’t give up their pets.”

Richard Searle, 75, and his dog Shadow were first in line at the January clinic.

“As long as my dog’s OK, I’m fine,” he said, adding that the veterinarians gave Shadow a clean bill of health.

Searle said he has lived in Ocean Beach since leaving the Army in 1968. He became homeless 10 years ago after his apartment burned down, and he said his Social Security checks and Army pension are not enough to pay for a new home.

Besides being his constant companion for 11 years, Shadow also is Searle’s protector.

“When we were camping in Northern California, he chased a bear out of my tent,” he said. “He chased him up a tree. He has no fear.”

Veterinarian Anri Benco said volunteering at the clinic is a chance to make a difference.

“For all of us vets, we understand how important the human/animal bond is, and for a lot of the homeless population, their pets are like their families,” she said. “It’s nice to be able to help them with that and make sure their pets are healthy.”

Geller said as the coalition grows, he would like the Street Dog veterinarians to partner with medical outreach physicians to provide health care to both pets and their homeless owners.

Upcoming events can be found on the Street Dog Coalition website, thestreetdogcoalition.org, or the group’s Facebook page.