David Crohan has been blind from birth, but that hardly kept him from crawling up on his grandmother’s piano bench at the age of two and finding that his fingers could extract marvelous melodies. Within a year he could sing and play a hundred songs from memory.

After an adolescence spent at the Perkins School for the Blind in Watertown, with emphasis on music training, his life became a whirlwind of solo recitals, chamber music performances and concert appearances with symphony orchestras.

It wasn’t until he turned 30 that Mr. Crohan, now of Palm Beach, Fla., and Oak Bluffs, began to latch on to the idea of acquiring a guide dog. “I was getting around fine with a cane,” he said in a recent interview on his summer-rental porch at the corner of Circuit and Tuckernuck avenues. David was seated on a rocking chair; Walker, an elegant, pale apricot-colored standard poodle, lay at ease atop the steps.

“Most of the dogs I knew were nuisances, spoiled and jumping all over the place,” Mr. Crohan said.

And yet one dog, a small, gentle poodle he’d taken from his mother when a stroke confined her to assisted living, became an unofficial guide dog. “I took this poodle everywhere. I was even able to pass her off as a service dog. She kept my left side protected, and my cane reinforced the right,” Mr. Crohan said.

He met a couple in Watertown, both blind, both with high-functioning German shepherds, who impressed him mightily. David also was married to a blind woman, Kate. Together they took the plunge and enrolled for nearly a month at the Guiding House for the Blind, north of Manhattan. David’s dog was a golden retriever named Skipper, Kate’s a black Lab.

“Skipper might have been a little young to start guidance. He was 18 months old, and he could still be distracted by the sight of a bird,” Mr. Crohan said. “But then he turned into a marvelous companion. He was perfect for my disposition: He didn’t deal with an obstacle until we were nearly on top of it, then he would work it out. A more nervous dog would have made me nervous.”

Meanwhile the Crohans, with an apartment in Watertown and a home in the Highlands of East Chop, had their first child, Stephen, in 1975. Mr. Crohan noted that the apartment was a little snug for a baby, two grownups and three dogs. Son Thomas was born in 1979, and Phillip in 1988. In those years there was a lot of canine cradle-to-grave activity. First the poodle died, then Skipper and Kate’s dog within a year of each other.

“Skipper was deaf, and he had heart troubles, but he worked up to the end,” said Mr. Crohan.

Oak Bluffs’s most fabled writer, Dorothy West, was a neighbor of the Crohans and reported Skipper’s passing in one of her Gazette columns. She noted that Skipper was loose in the yard and at play with the children. The fragrant scent of muffins steamed from the Crohans’ kitchen; Kate was a constant baker. Suddenly Skipper staggered, fell over on his back and lay still. Dorothy West knew instinctively he had died.

The children raced back into the house, then charged out again with a fresh-baked muffin. They waved it in Skipper’s face. His nose twitched. His eyes opened. The children fed him the muffin bit by bit. He finished and licked his chops. His eyes fluttered, then he died once more, this time for keeps.

The Crohans learned about a guide dog school in Connecticut called Fidelco where trainers brought dogs to clients’ homes. Both David and Kate acquired female shepherds. David’s was named Zanadoo, a name that quickly morphed into Zaney.

One of the practices the trainer imposed on both dogs and new owners was to place them in the middle of the street and drive a car straight at them.

“I had to phone the police that a maniac was about to run over two blind people with their dogs, just in case anyone panicked and called it in,” Mr. Crohan recalled. Clearly the dogs performed ably at removing their people from harm’s way.

Mr. Crohan reminisced about wonderful times with Zaney. “I would take the Bonanza bus into the city, and place myself and the dog right behind the driver. The minute the bus got rolling, I fell asleep and Zaney would go sit next to the driver. If the man happened to be wearing sunglasses, his boarding passengers were shocked to see an apparent blind guy behind the wheel of a bus. I think it nearly gave one man a heart attack!”

The pianist is strict with his guide dogs when they are in harness, and even off-harness he declines to pamper them like pets. Still, he said, “There’s a bond with a working dog that you don’t have with a pet. You’re moving together and experiencing everything as a team, as a perfect, living machine. It’s indescribable.”

Large working dogs tend to live until nine or 10 years of age. After Zaney lost mobility and had to be put down, Mr. Crohan acquired from Fidelco another German shepherd, named Witness. This new member of the family arrived at a time of transition: David and Kate had decided to separate. David and Witness lived in Providence, worked in Boston, and visited Arlington three times a week to visit the kids.

“Witness got three times the workout with all the traveling we did together,” Mr. Crohan said.

On one occasion, the two of them stayed with a friend of Mr. Crohan’s in Jamaica Plain, a neighborhood foreign to David. Once after a performance, a taxi driver dropped man and dog off at the wrong address. It was late at night, not a single set of footsteps tapped the pavement, and even if Mr. Crohan could miraculously stumble upon a working telephone, he would have no way to describe to his friend where he and Witness had been wrongly deposited. Yet the guide dog sent out vibes of knowing a definite direction. David followed his lead and after half an hour’s walk, Witness brought him to his host’s doorstep.

Eventually David met and married Claudette, who has grown kids and a Brussels griffon named Lily, a perky lap dog who is the opposite of a reserved service dog. All the same, Lily and Walker play happily together in the Crohans’ backyard in Palm Beach.

After Witness came another German shepherd, this one from a line bred by Hamilton Benz, father of Chilmark writer and musician, Merrily Fenner. David received Ms. Fenner’s blessings to name his dog Benzie, after her deceased dad.

Benzie had a small problem which was, ironically, that he was too big – 130 pounds. He was unable to squeeze himself into the floors of buses or automobiles. Benzie had a sweet and affectionate personality, but calluses on his elbows began to bleed and become infected. When Fidelco learned of Benzie’s difficulties, they recalled him and placed him in a family who could continuously dress and cover his calluses.

Mr. Crohan was discouraged enough to decree no more dogs. He reverted to day-and-night use of his cane, crossing busy highways even in the middle of the night. When Claudette heard that David had been observed wandering aimlessly (or so it looked) around Federal avenue, she urged him to get a new dog.

One day Mr. Crohan received a call from a man at the Freedom Guide Dog Foundation. He had a smooth-haired collie, white, whose voice box had been removed by its breeder (note: Island dog trainer Tom Shelby confirmed that this surgery is considered cruel by most professionals). David knew immediately that this dog would be wrong for him, beginning with the white hairs that would shed on the black tuxedos he wore when performing. Then the Freedom worker had an inspiration: He knew of a grown poodle who had been personally trained by a partially blind woman.

“She trained him well, but she moved at a faster clip than was comfortable for [the dog] Walker,” Mr. Crohan said. That suited the pianist perfectly, liking a slower pace. Walker required only three weeks of professional training to reach full sponsorship from guide dog school.

This Saturday at the Union Chapel at 8 p.m., the stunning Walker will be leading Mr. Crohan across the stage to a grand piano. Once the musician is seated, Walker will regally lower himself beside the bench. The poodle has no apparent preference for either the show tunes or the Chopin his master will be playing.

This will mark Mr. Crohan’s last performance on Island for the summer, then he and Claudette and their dogs return to Palm Beach for the fall and winter, a great arrangement for all concerned.