CHICAGO — For the last five years, a golden retriever has brought thousands of smiles to people in River North by walking himself.

Known for carrying his on leash on walks, Sporty has grown a large following on Instagram providing what owner David Duncan calls “street therapy.”

Now, the 12-year-old golden retriever is in the fight for his life. After a battle with small cell lymphoma last year, it has returned as large cell lymphoma in his GI tract.

“It is the worst thing in the world to see your dog in pain,” owner David Duncan said. “I just want to get him back to himself.”

Sporty is receiving care at MedVet on California Avenue. He recently received a medication called Elspar, which is is designed specifically for dogs with large cell lymphoma. It breaks down asparagine in the GI tract so that cancer cells will no longer be able to feed on it.

Duncan said Saturday it seems the Elspar is working, but progress is slower than vets hoped due to the fact that Sporty also has pneumonia.

If the treatment works, Sporty will begin chemotherapy soon.

“That would give him a better chance and a longer life,” Duncan said. “Reality is, it’s maybe another four to six months. But I’d do anything to get those months.”

With chemotherapy comes expensive medical bills. Duncan estimates treatment could exceed $20,000, so he started a GoFundMe. To his astonishment, fans of Sporty, local and across the country, started to donate.

“It just proves he is really loved and is a special dog,” Duncan said.

With over $15,000 raised in just a few days, Duncan said whatever is left over will go to an anti-cruelty society or other Instagram dogs battling severe illnesses.

The story of Sporty started back in 2007.

David Duncan moved to Chicago from Michigan and always wanted a male golden retriever.

Not having too many friends back then in the city, Duncan started going to agility shows with a co-worker who had a border collie and black lab.

“Every time I’d go to the events, I’d get distracted by the goldens,” Duncan said.

He eventually made friends with Katie McCullough, who had a golden retriever and knew many others with goldens too.

Years later, McCullough connected Duncan with Bill and Peggy Freeberg, who lived in Cedar Rapids, Iowa and place older goldens in loving homes.

“Sporty was their house dog, but was also into agility,” Duncan said. “He had a back injury and couldn’t do agility. They didn’t want to get rid of him, but he was the real alpha of the pack where they felt bad for other dogs.”

From the moment Duncan and Sporty met, it was “love at first sight.”

“I was instantly amazed at how awesome looking he was,” Duncan said. “It was love at first sight.”

Duncan took Sporty back to Chicago in 2014 and took some classes with him to develop a bond. Duncan said it was apparent Sporty loved to hold things in his mouth.

“Whenever he came over to me, he picked up a rug or towel and would always carry it around,” Duncan said.

After about six months, Duncan noticed Sporty would try to pick up and hold his own leash.

“’If I have to have this thing on me, why don’t I just carry it?’” Duncan said of Sporty. “‘Just give it to me, dad.’”

Duncan waited until night time in River North to do some test runs.

“It sounds weird, but he was a better dog when he was holding his leash,” Duncan said. “He was so proud of it.”

Sporty quickly started walking himself at all times of the day in River North, bringing smiles to all types of faces.

Naysayers may point out it could be dangerous for Sporty to walk himself, but Duncan said there’s never been an issue.

“I know some people think I’m stupid. The only way he’d get hit is if a car drove on the sidewalk,” Duncan said. “He’s not going to dart in the street.”

If Duncan ever saw someone who seemed uncomfortable by Sporty walking himself, he would take the leash.

Duncan admits Sporty has a weakness, but thankfully none are located in River North.

“He has a weakness for squirrels, but there’s none in River North,” Duncan said. “Back at my parent’s house in Michigan, it was funny to watch.”

As the smiles became more frequent and he started to get recognized, Duncan started up an Instagram account for Sporty called “sporty_thedog.” It rose from 5,000 followers to 30,000 to now over 75,000 admirers of Sporty.

“Sporty is the happiest when he is strutting himself and making people happy,” Duncan said. “I call it street therapy.”

Duncan recalled one time, a child in a wheelchair approached them as Sporty was walking himself.

“The child instantly perked up and loved petting Sporty. The dad was in tears,” Duncan said. “His ability to know if someone was having a bad day was obvious.”

Duncan continued to walk with Sporty everyday, until he noticed something was off in Jan. 2018.

“I was petting his neck and could tell something was wrong,” Duncan said.

Sporty was diagnosed with small cell lymphoma.

“We kept chugging along through the summer, but the mass was getting bigger,” Duncan said. “From a golf ball to a baseball.”

In Aug. 2018 on his 11th birthday, Sporty came back from a walk and could not catch his breath.

“We had him ready to be euthanized,” Duncan said. “He was being squeezed in the neck by the mass and to boot, he was born with an extra flap in his esophagus.”

He made it through the night, responded to chemotherapy and eventually the mass shrank.

Duncan knew though that even though Sporty beat his battle with small cell, a greater challenge was likely in the horizon.

“Ultimately, any dog that has small cell, the majority develop large cell lymphoma,” Duncan said. “Unfortunately, it’s a bigger beast.”

On Tuesday, Sporty developed bad diarrhea which turned into vomited. Duncan took him to MedVet Wednesday where he’s been diagnosed with large cell lymphoma in his gastrointestinal track.

“He knows I’m doing everything I can,” Duncan said.

As of Saturday, Sporty remains at MedVet and Duncan thinks he’s slowly responding to the Elspar he was given.

He’s going to stay in the hospital through Sunday morning, and may be able to come home soon to start chemotherapy.

With rising medical costs, Duncan is very appreciative of donations he’s receiving near and far.

“Whatever is leftover is going to help other dogs,” Duncan said. “Even if you can’t donate, just prayers and positive notes are great.”

Click here to donate to Sporty’s cancer treatment.

“If any dog can pull through this, it’s Sporty,” Duncan said.