The Ohio house of horrors where 16 “almost feral” children lived for years — allegedly locked away in a 12-by-12 room by their parents and grandparents — is a deplorable mess that reeks of cat urine.

The disturbing photos exclusively obtained by The Post show mountains of trash piled up inside the front room of the roughly 1,850-square-foot house in rural Hamden.

The only signs of decor or furniture appear to be a bizarre, framed painting of a tiger and a stained chest freezer.

Discarded boxes, moldy clothes and crumpled plastic containers are scattered across the filthy floor – along with a single Fireball Cinnamon Whiskey “Party Bucket.”

The walls, which were once white, are dingy gray.

In the basement, a dining room chair and a bicycle wheel are the only distinguishable items among a gigantic mound of trash that consumes half of the room.

Several more debris heaps surround the exterior of the five-bedroom, one-bathroom house, where only a few children’s items – including a small, broken bicycle and a copy of the kids book, “Jonathan James and the Whatif Monster” – hint at the crowd of children allegedly kept there for the past four years.

Two run-down vehicles — a silver sedan and a blue Chevy pickup truck — still parked outside the home appeared just as filthy, with images capturing dozens of cigarette butts, candy wrappers and other garbage littered across their interiors.

The photos show police tape still surrounding the property, more than a week after cops went to the house to carry out a warrant for an unrelated investigation on June 30.

What the found inside has shocked the conscience of Ohio — 16 children living in the feces-filled room, according to Vinton County officials.

The victims, aged 1 to 18, were mostly confined to the cramped space for at least the past four years, according to authorities, who have described the grisly scene as “deplorable” and “third-world” — and even said local livestock have better conditions than the kids did.

The children were taken to hospitals across Ohio after the rescue. Some were listed in serious condition, including two who were airlifted to trauma centers and at least one who had to be intubated, officials said.

The children, who were never enrolled in school, can barely communicate — and some cannot speak at all, authorities said.

The oldest child, 18, is developmentally disabled and unable to even write her name, according to investigators.

Grandparents Gary Siders Sr., 73, and Christina “Lynn” Siders, 67, were arrested alongside their son, Gary “Bub” Siders Jr., 36, and his wife, Elizabeth Siders, 33, and each slapped with 16 counts of felony child endangerment charges.

The younger couple is believed to be the biological parents of all 16 children, officials said.

Elizabeth was just 15 when she married Gary Jr., then 18, in 2008. Their oldest child, the 18-year-old girl, was reportedly born two months later

The mom once gave birth to conjoined twins who died hours after delivery, state records show.

The owner of a local food truck, Papis Pizza, said Elizabeth and Gary Jr. often swung by to order pies — and stunk up the place.

“They just smelled like cat…like cat piss. Bad,” the man, who gave the name John John, told The Post. “They both stink. They both needed a shower.”

“You could walk behind them and smell them,” agreed his wife, Corissa Gonzalez.

The duo — who never saw the Siders with their children — described Elizabeth as eerily quiet.

“You tried to talk to her and she didn’t say nothing… I don’t think she was allowed to talk,” John said.

“You would have never been able to tell she had 16 kids. She was a skinny girl,” Gonzalez explained.

The four defendants have all pleaded not guilty to the charges and waived their preliminary hearings scheduled for Tuesday afternoon.

Elizabeth, Gary Jr. and Christina are currently being held in county jail, each on $300,000 bond.

Gary Sr. was facing the same circumstances until Tuesday, when a judge changed his bond conditions after he was taken to the hospital with a “serious medical problem,” Vinton County Prosecuting Attorney William Archer revealed during a news conference Wednesday.

Siders Sr.’s new “recognizance bond” will ensure he gets medical treatment, but since he’s technically no longer a jailbird, the county won’t have to pay for it, according to Archer.

If he gets released from the hospital, he won’t go back to lockup – instead, the state will pay for him to be strapped with a GPS device in order to monitor his movements, according to the attorney and court documents.

If convicted on all charges, each defendant faces a maximum sentence of up to 192 years in prison.