No one knows this better than April Soderstrom, or, as she’s recognized in the South End, the blonde tooling around with a 35-pound French bulldog in a jogging stroller.

“Sometimes people make snide remarks,” said Soderstrom, 28, an executive assistant who also designs and markets her own line of jewely. Or they point and laugh, and hint that 5-year-old Louis is a “diva.”

Let the public mock. The white dog with the big pink ears has long struggled with a bad back and hips, but he got around OK until a few months ago when he injured a knee, making the two-block walk to the park impossible. “But I wanted to keep him happy,” Soderstrom said.

She carried him back and forth for a while, but that was exhausting. Enter a $130 dog stroller from eBay. “Louis loves it,” she said. “He stands right next to it waiting to be picked up and put in.”

It’s probably too early to declare pets-in-strollers a full-blown trend, at least in Boston. (In certain neighborhoods in Manhattan, Los Angeles, and southern Florida, the unusual dogs are reportedly the ones who are walking.) But the warning signs are building:

Two Pekingese pups were spotted recently in a stroller in the Prudential Center. A Yorkie was seen riding in the South End, where a cat was also observed taking a drive. In Cambridge, a long-haired dachshund was parked in a stroller in front of a Star Market. Reports of stroller dogs enjoying Castle Island and the Gloucester waterfront have also come in.

At the pet-friendly Boston Harbor Hotel, canine guests have begun arriving in strollers, particularly in the winter, the better to protect their paws from ice-melting salt. “It’s a nice easy way for them to get around,” said concierge Rob Fournier. (A stroller even helped one guest sneak a pooch into the hotel’s Rowes Wharf Sea Grille, a jaunt that lasted until a staffer noticed that the body in the stroller was a tad furry.)

And a dog stroller made the iconic September issue of Vogue magazine. “Two days before my dog Rose died, I put her in the stroller and pushed her down the sidewalk,” the best-selling author Ann Patchett wrote. “When my friend Norma bought Rose a dog stroller the summer before, I hadn’t wanted it, but feelings of idiocy were quick to give way to Rose’s obvious pleasure.”

The stroller movement is the natural outgrowth of several other pet-related story lines, including an increase in spending on pet health care, a growing population of elderly pets, and an increasing belief that our pets are not our animals, but rather our children.

In 2001, US pet owners spent $7.1 billion on pet health care, a number that jumped to $13.41 billion in 2011, according to the American Pet Products Association. Along with that spending has come an increase in the percentage of senior pets who, having benefited from life-prolonging therapies, need help getting around.

In 1987, forty-two percent of dogs were 6 years old or older, according to the American Veterinary Medical Association. In 2011, that number had risen to 48 percent. The percentage of senior cats is growing at an even faster rate. In 1987, 29 percent of cats were 6 years old or older. By 2011, 50 percent of cats were “of a certain age.”

But strollers aren’t just for infirm or elderly pets. Some are for perfectly mobile pets who are more child than pooch. Because dogs can be zipped securely into their strollers, the carriages allow pets to accompany owners on an entire day’s worth of activities.

“We like to include our dogs in what we do,” said stroller-user Debby Vogel, the owner of three Chihuahuas, a 14-year-old with mobility issues, and two 9-year-olds who know a good thing when they see it. “The girl is lazy,” Vogel, the Animal Rescue League of Boston’s volunteer services manager, said of one of her younger dogs, “and the boy is nervous when people loom over him. In crowds he gets freaked out.”