Julianne Mangin knows where the bodies are buried. Not all 50,000 of them, but enough to turn a stroll with her through Aspin Hill Memorial Park into a fascinating rumination on how much we love the Mickeys, Shastas, Snowballs and Macaronis of our lives.

Mickey, Shasta, Snowball and Macaroni are — were — dogs and cats. They are buried at Aspin Hill, a 99-year-old pet cemetery near Georgia Avenue and Aspen Hill Road in Silver Spring.

Mangin, 63, a retired librarian who grew up nearby, has become the unofficial historian of the place, telling stories of the residents and their owners at petcemeterystories.net. She visits frequently, seeking to uncover graves — literally and figuratively.

“This is my aerating tool from Home Depot,” Mangin said on a recent weekday afternoon, pulling a long, four-pronged gadget from the back of her Subaru.

Many of the old stone grave markers have sunk into the ground and become covered with dirt, grass and leaves. When Mangin sees a depression in the earth, she deploys her tool.

“You push the aerator down until you hear a ‘clink,’” Mangin explained. “The prongs are four inches deep. I really don’t want to find anything lower than four inches. And if I find nothing, at least the soil is nicely aerated.”

Aspin Hill — it’s named after a kennel in England, thus the spelling — was founded in 1920 by Richard and Bertha Birney. It was the only animal cemetery within 200 miles of Washington, attracting well-heeled pet owners wishing to memorialize their pets.

They were people like Selma Snook , who — after throwing elaborate wakes — buried poodles Boots, Buster, Trixie and Snowball in a family plot, their tombstones arranged side by side and enclosed with a low metal fence.

There’s a single headstone just outside of where the now-rusted fence once stood. Mangin thinks it might be for Snook’s cat.

“I was told the cat was buried there because it didn’t get along with the dogs,” said Mangin.

Why should we expect animals to be any different in death than in life?

Mangin led me to the grave of a collie named Pal, who died on Aug. 15, 1928.

Died? Well, it’s more complicated than that. “He preferred death to life away from his master,” the inscription on Pal’s stone begins. “This ever faithful barking ghost may leap to lick your phantom hand.”

A bit creepy. And there’s no denying there’s a creepy vibe to the place. Aspin Hill is in the nicest shape it’s been in years: the grass mowed, many of the tombstones cleared and cleaned. But all cemeteries are mementos mori — reminders of death — and it’s no different here.

The story of Pal, though, is particularly dark. The 13-year-old dog was owned by Mr. and Mrs. Eric Matus of Capitol Heights, Md., who drowned when their skiff overturned in the Potomac. Pal was reportedly inconsolable, refusing to allow anyone to approach and ignoring food left for him.

It was said that Matus had left instructions for the dog to be euthanized if he and his wife died. Dozens of people protested the dog’s execution, offering to take in Pal.

“But these good people did not understand,” Mrs. M.R. Blumenberg of the Animal Rescue League told The Washington Post. “Pal could never be happy again. Anybody who saw the look of anguish in his eyes would know it. I have seen collies in somewhat similar circumstances slowly die of broken hearts.”

A week after the Matuses’ death, Pal went to the great kennel in the sky.

There’s a sunnier story behind Napoleon, a white Persian cat hailed as the “Weather Prophet of Baltimore.” Owner Fanny de Shields noticed that whenever Napoleon changed his sleeping position, rain would fall within 24 hours. When a story ran in the Baltimore Sun in 1930 noting the moggy’s meteorological prowess, de Shields was inundated.

“She had to field calls from farmers and people planning outdoor weddings,” Mangin said.

The cemetery covers about eight acres. It has passed through the paws of several owners over the years — including PETA’s — before it was donated in 2007 to the Montgomery County Humane Society, which plans to build its headquarters on a two-acre parcel that contains no remains.

Mangin is delighted to debunk some of the tales that have grown up around Aspin Hill. Yes, J. Edgar Hoover’s Airedale Spee De Bozo is buried here, but Petey, the dog from the “Our Gang” movies, is not.

Mangin thinks people were confused by a tombstone reading “General Grant of R.K.O.” RKO was a studio, though not the one that made the “Our Gang” films.

Said Mangin: “Petey is buried in Los Angeles, because why would you fly a dead dog across the country when there are pet cemeteries in Los Angeles?”

Of course, there’s little we won’t do for our pets, even in death. Andy, a capuchin monkey, is buried under a tombstone adorned with his color photo. He’s dressed in blue pants and a pinafore.

“I will always love you,” reads the inscription.

Is that the owner talking about Andy, or Andy talking about the owner?

Aspin Hill is open during daylight hours. Mangin will give a talk on the cemetery on Oct. 4 at 7 p.m. at the Gaithersburg Community Museum. For reservations, visit gaithersburgmd.gov and click on “More Events.”

Twitter: @johnkelly

For previous columns, visit washingtonpost.com/john-kelly.