WARNING: Some of the details included in this story may be upsetting to some. Viewer discretion is advised.

UPDATE: The Humane Society of Northern Utah confirmed Thursday evening that Sage the cat has died as a result of the injuries he suffered during his ordeal.

A reward for information leading to an arrest and conviction in the case has been increased to $30,000 thanks to gifts from various donors.

Previous story continues below:

CLEARFIELD, Utah -- The owners of a Clearfield cat are sick with shock after he went missing for days then came home with what veterinarians and the Humane Society of Northern Utah are calling the worst case of animal abuse they’ve ever seen.

If a cat has nine lives, Sage could use all of them right now, as he barely hangs on to life.

“It's heartbreaking,” owner China Cassel said. “We all sat around him and we cried because we didn't know what to do.”

She said Sage disappeared on Saturday, and her sister discovered him early Wednesday morning in their home.

They said he must have given it his all to get inside.

“He had to have—with his injuries--hopped over that [fence], climbed through the dog door and just barely made it to the bottom of the stairs,” she said.

Normally, the 6-year-old grey and white, fluffy family member is always asking for love and attention.

“He's one of the lights of our lives,” Cassel said.

But on Wednesday, he looked unrecognizable, and couldn’t move or meow.

Cassel said his eyes were swollen shut, and his fur had been chopped up.

“He's missing a lot of skin. You can see his bones,” she said, describing Sage’s injuries. “His whiskers were clean-cut.”

The family also noticed what looked like hot glue or silicone caulk stuck to his body, and in areas like his rectum.

“Our biggest fear was that they had injected it into him,” she said.

They also saw a black collar around Sage’s neck that didn’t belong to the family. That’s when they realized that someone had most likely done this to Sage on purpose.

The Cassel family rushed Sage to the vet, and the Humane Society of Northern Utah (HSNU) got involved.

“They broke his ribs, his little toes, beat his face, glued his eyes shut, tried to glue his penis and anus shut, burned him with hot glue, and put silicone on him,” Debbie Barnes, HSNU president, said in a press release. “This is the worst abuse case I have ever seen.”

Dr. Wynn Palmer with Animal Care Veterinary Hospital in Roy agreed.

“I've never seen anything like this in terms of potential abuse,” he said.

He didn’t know if Sage could survive.

“There were multiple wounds and infections on the cat’s body. One of the paws was fractured,” he said, describing some of the injuries.

On Wednesday night, Sage was transferred to Advanced Veterinary Care, a 24-hour Level I trauma facility in Salt Lake City.

Cassel said Sage has been stabilized, and will be monitored through the night.

She said the facility’s goal is to make him comfortable because of his pain, and if he is still stable Thursday morning, they might be able to begin looking at possible treatments or surgeries.

The horror of watching Sage suffer is excruciating for the family, especially because they don’t know who did this.

“What's sickening the most is we don't know why it happened,” Cassel said.

The only thing that brings them comfort now: Sage found his way home, perhaps just in time for his family to try to save him.

“It takes a strong animal or person to go through that and still find their way home,” Cassel said, later adding, “He knew where home was. Even when he couldn't see, he still knew he could come home and be safe.”

In a press release, the Humane Society of Northern Utah said they are offering a $5,000 reward to help solve this felony crime.

“This gratuitous torture of a cat has us at a loss for words,” Deann Shepherd, HSU representative, said in the release. “It is disgusting and frightening that someone or some people would intentionally cause this much pain and injury to a helpless creature. As one of the most extreme cases of animal torture we’ve seen, we hope that someone will come forward with information to hold the person responsible for their actions and remove them from the community before they cause any further harm.”

Anyone with information is urged to call Davis County Animal Services at 801-444-2200 or John Fox, HSU chief investigator at 801-261-2919 ext. 210. Tips can remain anonymous.

The Humane Society of Northern Utah is accepting donations as they pay for all medical costs to keep Sage alive.