Condolences have poured in for a Louisiana couple who successfully battled wildlife authorities to keep their domesticated nutria as a pet, watched the semi-aquatic rodent appear on cable news and accumulate a social media following tens of thousands strong, and then endured the animal’s recent death from cancer.

Denny and Myra Lacoste announced Neuty’s death on Monday on Instagram, where more than 37,000 users followed an account dedicated to documenting the nutria’s life.

“Neuty passed away peacefully in his sleep Saturday morning on one of his favorite rugs,” the announcement read. “We are devastated and our hearts hurt.”

One reply to the post that was representative of the various others said: “What an exceptional creature he was, with the very best family! He’ll be so dearly missed.”

Another came from the popular New Orleans-based brewery Urban South, which said “we always loved having Neuty” at the business.

The uniquely south-eastern Louisiana saga of Neuty began on Christmas Eve 2020, when he was a days-old baby and the Lacostes found him on the side of a road divided by a drainage canal in their home town, the New Orleans suburb of Metairie. Some of his siblings had just been fatally struck by a car. And it seemed he would have died as well, as the Guardian reporting partner WWL Louisiana has previously written.

Resembling more diminutive capybaras, nutrias are considered to be part of an invasive species. The beaver-like creatures notoriously damage everything from the state’s crops and its marshes to its fragile coastline.

But Denny Lacoste told the outlet that Neuty won his heart on sight. The seafood purveyor gave Neuty pet milk for several weeks and potty-trained him to a healthy weight upwards of 20lbs (9kg), and the animal essentially became a family member.

Eventually, though, Neuty’s story received news coverage. Louisiana’s wildlife and fisheries department attempted to confiscate Neuty, citing laws governing wild animals. But, met with public outcry and a Change.org petition named “free Neuty” that drew more than 17,000 signatures, the authorities granted permission for the nutria to live with the Lacostes as a pet.

The struggle pitting Neuty and the Lacostes against the government won the rodent a level of social media fame that many influencers would envy. He appeared on Tucker Carlson’s Fox News show in April 2023, mere days before the host and the network went their separate ways.

“I’m glad to meet Neuty,” Carlson said to the Lacostes at the time. “I just want to thank you on behalf of all animal lovers for your bravery in the face of state interference.”

Neuty more recently made appearances at local schools, fairs, festivals and farmers’ markets as social media pages tracking his life gained popularity and event invitations poured in. He was known throughout his Metairie neighborhood of Bucktown and well beyond for displaying calm behavior with children and other people surrounding him, gazing at him and petting him – occasionally dozens at a time.

He could be seen being led on a leash by the Lacostes and stopping to take pictures with Mardi Gras parade-goers young and old in mid-February.

But less than a month later, on 11 March, the Lacostes revealed Neuty had been diagnosed with an inoperable, cancerous tumor.

He was cleared for radiation treatment as his cancer spread, as WWL reported. Yet on Friday, the Lacostes noticed an unspecified change in his personality, they said. He had one last of his preferred milk bone treats on Saturday and died roughly an hour later.

“We could go on and on about the joy [and] happiness Neuty has brought … [for] 5½ years,” the Lacostes wrote in their announcement of Neuty’s death. “We are heartbroken and miss him terribly & will continue to miss him, but will never forget the great times we shared with him, he literally made us laugh every single day.”