"I think more than food or water, companionship is lifeblood to a dog," O'Sullivan said. She is convinced that when an older dog is adopted, they will live longer because of an owner's love.
Many shelters and rescues online and off focus on senior dog adoptions that are growing in popularity. But O'Sullivan's page, Susie's Senior Dogs, has gotten more attention than most thanks to a big boost from her boyfriend, an Internet star who knows how to build buzz online — and owns a dog named Susie.
Brandon Stanton of Brooklyn is the author of a book and much-read blog called "Humans of New York," which claims more than 4 million followers on social media and chronicles the lives of New Yorkers, enrapturing overtaxed Web surfers with heartfelt photos and snippets of text.
Three years ago, Stanton adopted an 11-year-old Chihuahua named Susie.
"She is the greatest dog in New York. ... I didn't realize what it meant to have an animal attach itself to you so her only concern in life is being close to you," he said.
O'Sullivan had set up a Facebook page for Susie, which had about 10,000 "likes" the morning she changed its purpose to finding other old dogs new homes. Stanton pitched the page on his blog, and by nightfall the page had 10 times as many followers. That number has since grown to over 150,000, and she has helped nearly 200 dogs since January.
That includes a 12-year-old pooch that Britany Spangler of Grand Rapids, Mich., found on the page.
"I never intended on getting a dog until I saw our Molly and I knew we had to have her," she said.
The Lhasa apso was missing a whole side of teeth, was infested with worms and fleas, had an allergy that made her hair fall out and suffered kidney problems.
Despite the health issues, the dog gets along beautifully with her three children, who are all under 3 years old, Spangler said.
"It was like they had been together forever," she said. "She came potty-trained and full of love. If she is with us for six months, she blesses us for six months. If she is with us for five years, she enriches our lives for five years. She's the dog I never knew I needed."
Steve Greig, who owns a menagerie of animals, found a 10-year-old dog to love on O'Sullivan's page, but the nearly hairless Chihuahua-poodle mix named Phyllis also came with problems.
The dog is blind, weak, had sores on her face from trying to escape her cage, and lost all her hair to an infection, Greig said. In February, he took in Phyllis because he didn't have hope she would be adopted from a shelter otherwise.
"She looks like a fox with a bad perm," he said, but that hasn't bothered his dogs, cats, chickens, ducks or pot-bellied pig. "The other dogs must realize the 10-year-old Chihuahua-poodle is blind and feeble. They are so gentle with her. She's fitting in fine."
Greig is looking into getting Phyllis surgery to possibly restore her eyesight.
Meanwhile, O'Sullivan and animal rescue owner Elli Frank are trying to help Tanya, an 8-year-old pit bull mix that was all but forgotten after being dumped at a shelter as a puppy.