BOSTON (SHNS) – A loyal State House employee is set to retire this month after more than eight years working on Beacon Hill — and that’s around half a century in “dog years.”

Merrick the guide dog is a familiar sight to anyone who regularly walks around under the Golden Dome. He accompanies Carl Richardson, the State House’s Americans with Disabilities Act coordinator who identifies as DeafBlind.

The pair are together all day, every day, while Richardson endeavors to make sure the state capitol is accessible to people of all abilities.

But there are signs that Merrick’s getting older, like how he’s “getting sniffy,” Richardson said Thursday as the black lab paused to investigate a distracting scent on Bowdoin Street.

So the veteran Beacon Hill canine will be hanging up the harness on March 15. Like any good State House coworker, Richardson wants to plan a retirement party for his friend. He’s thinking of having a time for Merrick at the 21st Amendment after work that day.

It’s been a long road for Merrick, starting around a decade ago with a test to see how much “potential” he had when he was eight weeks old.

From there, potential guide dogs go to a foster family to be socialized and gain basic obedience training. Another test gauges suitability for guiding, and after passing that hurdle, the dog is trained for his or her new career for a minimum of 16 weeks. Around 800 dogs are trained, but only around 200 “make it,” according to Richardson.

If Merrick has his party over at the 21st Amendment in a couple weeks, maybe some of his cousins could stop by.

Merrick comes from Guiding Eyes for the Blind in Westchester County, N.Y., the same training school that the Massachusetts State Police bomb-sniffing dogs originate at before they “career-change” and go into law enforcement, Richardson said, “so he’s probably related to all the bomb-sniffing dogs here, like a distant cousin.”

Richardson will be able to keep Merrick as a pet at home, he said, something he’s thankful for because not all blind people have that ability. But the retirement still gives him pangs of melancholy.

“I have mixed emotions right now, today as we speak. Because I’m retiring my best friend, who’s with me all the time. And it means that he’s getting older,” Richardson said.

The day after Merrick’s retirement, March 16, is Presentation Day. That’s what they call it when the trainer rings Richardson’s doorbell and presents him with his new guide dog. It’s the big reveal — until then, he won’t know his new companion’s gender or name, just that he or she will most likely be a lab.

As for Merrick’s thoughts on his new chapter?

“I don’t think he’ll miss the day-to-day grind, I think he’ll just wonder how come he’s not hanging out with me,” Richardson said.

The black lab has faithfully guided him through the subway, around the State House, and as far abroad as Europe and San Francisco.

When the new dog comes on Presentation Day, the basic language will be the same — the commands are the same — but there will be a new personality to work with. The way they interact will be different than with Merrick, or with his predecessor Kinley, who worked with Richardson from 2006 to 2014.

“When things are right, you’re almost as one,” Richardson said. “You’re almost reading each other’s thoughts. I can’t explain it. It’s the most — when things click, it’s the most amazing feeling in the world.”