Roy Rogers and his trusty steed Trigger may have come to the end of their "Happy Trails" – television’s most famous horse is going on the auction block, The ENQUIRER has learned exclusively.

The beloved golden palomino’s home, the Roy Rogers-Dale Evans Museum, has closed – doomed by bitter family feuding, greed, mounting debts and IRS demands.

Trigger – stuffed in a familiar pose, rearing majestically on hind legs – will join Dale Evans’ horse Buttermilk, their beloved German shepherd Bullet and other Rogers memorabilia in bidding that’s expected to reach into the multimillions of dollars.

Fans around the world were stunned by the news that the museum in Branson, Mo., abruptly closed its doors on Dec. 12 after being open to fans for 42 years.

"Negotiations are underway for Trigger, Buttermilk and Bullet to be sold at auction in New York next summer," an insider told The ENQUIRER. "The IRS has valued Trigger alone at $1 million – not bad for a horse Roy paid $25,000 for when he was alive!

"The other animals are expected to raise another $500,000 and the rest of Roy and Dale’s most treasured possessions – including guns, saddles and memorabilia – could fetch another $6 million."

Roy, Dale and the animals became the stuff of Hollywood legend after starring in more than 100 movies *many of them for Republic Pictures) and The Roy Rogers Show on radio and television.

The "King of the Cowboys" died in 1998 at age 86, and his wife Dale passed away nearly three years later.

"Roy’s son Dusty was devastated when family members started feuding over getting money from the estate," said the insider. "The problem was that the entire estate was tied up in the museum. They’re a very Christian family, and Dusty never dreamed greed would help doom the museum."

In desperation, as the recession cut into attendance at the museum, Dusty appealed for help from many of the old-time Hollywood stars who’d known his dad, say sources.

"He wrote to Kevin Costner, Clint Eastwood, Robert Duvall and Tom Selleck, who’d all known his dad, as well as Clint Black and Randy Travis, who recorded with Roy on the last CD he made before his death," revealed the insider. Dusty did not get enough of a response to save the museum.

In a statement he issued when the museum closed, Dusty hinted at the family turmoil that led to the closure, saying there were "many very emotional and financial issues" involved.

"Dad always said, ‘If the museum starts costing you money, then liquidate everything and move on,’" he said.

"Please keep us in your thoughts and prayers – remember, Roy Rogers and Dale Evans WILL live forever in our hearts and minds.

"I leave you all with Dad’s favorite saying: ‘Goodbye, good luck, and may the good Lord take a likin’ to ya!’"