As an adult, she channeled that love into volunteer work at the San Francisco humane society. She was ultimately walking dogs there five days a week.

That's when she noticed the older dogs were not being adopted.

"Most of them would end up getting euthanized," Franklin said. "They didn't stand a chance compared to the puppies."

The plight of these senior dogs broke Franklin's heart.

"I could feel their hope draining and my hope draining with them," she said.

So in 2007, Franklin started Muttville out of her home. The nonprofit rescues senior dogs from shelters and finds them forever homes.

JUST WATCHED Top 10 CNN Hero Sherri Franklin Replay More Videos ... MUST WATCH Top 10 CNN Hero Sherri Franklin 02:24

The group now has its own facility and has adopted out more than 4,000 senior dogs.

Some dogs come to Muttville because their owner passed away or cannot care for them. Each week, the group gets around 150 requests from shelters or individuals to take their elderly dogs.

At Muttville, the dogs roam in large rooms filled with big beds and couches. The organization also has a network of more than 100 foster families, allowing more dogs to be saved.

"They have so much to teach us. I've learned to be present and live in the moment," she said. "They've taught me to let the little stuff fly."

CNN's Meghan Dunn spoke with Franklin about her work. Below is an edited version of their conversation.

CNN: Senior dogs can need a lot of medical care. How does Muttville handle that?

Franklin: We have our own vet suite at Muttville. Every single dog that comes in sees our vet. They get de-fleaed, dewormed; they get their full vaccines and microchipping. And then we go a step further, doing full blood panels and urinalysis. We do that all in-house now, which has just saved us so much time and gotten the dogs ready for adoption so much quicker.

From the moment they arrive at Muttville, if they're in pain, we're going to do something about it. We want our dogs to experience the most health they can have. Some of them are not going to be as healthy, and some of them we can't completely fix. But we're going to give them the best quality of life that we possibly can.

CNN: You've started matching senior dogs with senior citizens. Why does that pairing work well?

Franklin: We get a lot of phone calls and emails from children who have an elderly mother or a father who's living alone. We often hear stories like the husband died and they don't get out, they don't walk anymore, they don't know their neighbors.

I hear how adopting one of our elderly dogs all of a sudden has gotten the father to start walking and getting to know his neighbors. He has something to talk about, he's getting exercise, and he has somebody that sits and watches TV with him at night. Everything from their social skills to their actual health has changed. They have a community now of other dog lovers.

CNN: Your group also has a special program for terminally-ill dogs.

Franklin: We call it Fospice—that's hospice and foster mixed together. Every once in a while, we get dogs that have a terminal or untreatable disease. Muttville stays committed to every dog that comes here. We find them homes with great families, and we cover the cost of palliative care for the dog until the dog passes away.

JUST WATCHED CNN Hero Sherri Franklin: Doggie hospice Replay More Videos ... MUST WATCH CNN Hero Sherri Franklin: Doggie hospice 02:17

We have about 40 dogs right now in that program. We think, "Oh, the dog might live two months." But once it gets into a loving home, the dog's there for two years. Others pass away much earlier on.

We thought we wouldn't have a lot of people who would actually sign up for something like this. And what I get back from people in our Fospice homes is how rewarding it is to give an animal a happy last chapter.

CNN: Is it emotionally hard knowing these older dogs may not be in your life for long?

Franklin: It is not about the quantity of time, it really is about the quality of time you spend with your animal. I did adopt a 15-year-old Dalmatian. He may have been the love of my life. I had him for about a year and a half, and that was the happiest time. And I know it was the happiest time for him.

A lot of our adopters who have adopted over and over again, they do it because they fall in love with a dog and they want to share that time. They want to give that dog a special home, special love. And when it's time to say goodbye, it's always hard. But you got to share that part of your life with an animal that gave you unconditional love. Nothing beats that.

Want to get involved? Check out the Muttville website and see how to help.

To donate to Muttville, click the CrowdRise widget below.