Michael Zuckerman said he was thrilled when Ms. Otten asked permission to bring a dog to an open house at the former home of his late aunt at 80 East End Avenue, which he had been tasked with selling. The building is dog-friendly, and Mr. Zuckerman said that even if Ms. Otten brought a big dog, “what better way to demonstrate that all kinds of dogs are allowed in the apartment than to have one present at a showing?”

Ms. Otten has helped place 15 dogs in permanent homes in the last three years. Word of her work on behalf of rescue animals also has helped her drum up some real estate business.

When Eileen Mandel, a retired fashion designer from Milwaukee, started her search for a pied-à-terre in Manhattan, she sought out Ms. Otten. Ms. Mandel and her husband, Barry, have three rescue dogs, including one adopted from a shelter in Puerto Rico. So securing a pet-savvy broker was an absolute must. “My top priority was finding a place that would accommodate all of my dogs,” Ms. Mandel said.

With Ms. Otten’s help, she bought a one-bedroom co-op in the Hampshire House at 150 Central Park South in 2017. “I just feel like when you meet someone that’s so dedicated to helping animals in need, there’s a certain level of trust present that doesn’t need to be built over time,” Mrs. Mandel said. “You already know they have a good heart.”

The presence of a four-legged companion doesn’t necessarily help sell a property, but “even if a potential buyer doesn’t want to adopt, bringing the dogs on showings still helps generate leads,” Ms. Otten said. “Having a cute little thing running around brings a levity to the whole experience.”