Dirk was a Hurricane Katrina survivor. Vito's guardian was left unable to care for him after a car crash. Tami was a runaway, roaming the streets of downtown Baltimore when a do-gooder took her to a shelter.
Just a couple of years ago, all three were down on their luck, dogs that, like mine - a stray named Ace who landed in the city shelter - were in need of a hand.
Now all four are lending one.
Ace qualified earlier this summer to become the newest canine member of Karma Dogs - one of several organizations in the Baltimore area, and a burgeoning number nationwide, that are using dogs to teach, train, rehabilitate, heal and comfort.
In addition to the estimated 40,000 "service" dogs assisting people with disabilities in the United States, there are tens of thousands more assisting in smaller ways - helping children overcome reading problems, visiting the elderly and ill in nursing homes and working with people with disorders ranging from autism to Alzheimer's.
As a member of Karma Dogs, a nonprofit organization that uses only "rescued" dogs, Ace has worked in two programs.
At the League for People with Disabilities, he has been part of a program that uses dogs to help connect with, and teach social skills to, people with autism.
And from June until recently, he visited the Towson Public Library every Saturday in what has become an increasingly popular type of program nationwide - one based on the concept that children can improve their reading skills and confidence levels by reading to a warm, accepting, nonjudging, noncorrecting dog.
There are other therapy-dog opportunities in the Baltimore area - including several programs that bring dogs into hospitals, nursing homes and other institutions. In addition to providing a little cheer, time with a dog has been shown to help people with depression, high blood pressure and heart conditions.
I chose Karma Dogs because I liked the name, and the whole "paying it forward" concept, and because it was less expensive than some of the other therapy-dog opportunities I had investigated a year earlier, but not pursued.
It cost $75 to enroll in Karma Dogs; the fee covered the necessary ID tags, Ace's official Karma Dogs bandanna and - the first step - having Ace evaluated by a professional dog trainer.
Liz Hauck, of Drop the Leash, visited my home, had me show her my dog's repertoire of tricks, and put us through some drills aimed at gauging Ace's obedience, which needs work, and his temperament, which is almost always calm and gentle.
From there, we headed to the local park, where Hauck, one of two trainers Karma Dogs contracts with, observed how Ace got along with other dogs.
Except for not coming when I called him a couple of times, he behaved well, was gentle with little dogs that jumped on him and responded to most of Hauck's commands.
A second meeting was set with Hauck at the PetSmart in Towson, which, crowded as it can get on weekends - with dogs and people - would serve as a test to see how Ace reacted to crowds, loud noises and low-level chaos.
There, as Karma Dogs founders Kelly and Andrew Gould looked on, Ace was bumped into with shopping carts, exposed to loud noises like dropped clipboards and nudged in the side a few times to see how he would react.
At one point, at Hauck's instruction, Andrew Gould loudly approached Ace with his arms flailing to make sure Ace would keep a cool head when around people with behavioral issues.
After a good hour in PetSmart, Hauck took Ace outside to chill out, and after a walk around the parking lot pronounced him qualified. (Not all dogs qualify as quickly as Ace did, Hauck said. Some require further training at additional expense.)
There were two more training sessions after that - for me, not Ace - one to review our role in the autism program, another for the library program.
On our first visit to the League for People With Disabilities, we approached several of the program's clients, some of whom wanted nothing to do with a dog as big as Ace.
One teenage boy, though, petted Ace, walked (and ran) him on a leash around the circle in the courtyard several times, then brushed him.
Small as those achievements might seem, they were, for him, progress, Kelly Gould said. With autism, progress is measured in small increments.
"One of the kids I've worked with since January, when I originally met him, wouldn't make eye contact with me or come near the dog," said Gould, who uses her dog, Dirk, in the program.
"But after working with him for about eight months, he's happy to see the dog, greets the dog and hugs me. Before, Dirk and I couldn't hold his attention for 15 seconds; now he will help walk the dog for several minutes at a time."
Using dogs in therapy with the autistic is a relatively new method, Gould said.