The head of the NYPD’s Mounted Unit had three retired police horses put down at a Pennsylvania farm — as shocked veterinarians and animal-cruelty officials watched in disbelief.

Capt. Barry Gelbman gave the highly questionable order to fatally inject three of the Finest’s former workhorses while personally supervising the move of 30 police horses from the Abbottstown stable to two other farms, sources said.

The steeds — Danny, Willis and Richie Rich — were 15 to 20 years old but had life expectancies of up to 30. They were being treated for various leg ailments, which meant they could not endure standing in a cramped, 15-horse transporter for the 12-hour ride to their new homes in either upstate New York or New Hampshire.

Two of the horses were being treated for abscessed legs, while the third had a swollen hind leg.

The stable owner had informed Gelbman in advance that several of the horses would have problems traveling, sources said.

But instead of leaving the horses behind to heal or even putting them up for adoption, Gelbman made it clear the animals were department property that he controlled — and he ordered the otherwise healthy animals put to death, sources said.

“They did not need to be euthanized,” one source insisted. “They just could not travel cramped for 16 hours. They only needed special accommodations to move them.”

Another source quoted Gelbman as saying, “Well, if they can’t be moved, then they are not going to be taken care of . . . Put them down.”

Attempts to reach Gelbman were unsuccessful.

NYPD spokesman Deputy Commissioner Paul Browne said, “The commanding officer of the Mounted Unit conferred with a private veterinarian at the scene who stated that based on the age and current health of the horses, it would be inhumane to transport them.

“Additionally, the doctor expressed concern of the stress placed on the horses being integrated into a new herd, given their existing medical conditions.”

In late 2005, the NYPD learned that 58 retired steeds were malnourished at a farm in upstate Otisville that was falling into bankruptcy.

The department found adoptive homes for most of them. It then solicited bids for the remaining ones in a process later unmasked by The Post as corrupt.

The largest portion of the contracts — worth $2.5 million over 10 years — was awarded to Victoria Nanninga, who was the then-secret girlfriend of the Mounted Unit’s quartermaster, Detective Richard DePamphilis.

Nanninga and DePamphilis pleaded guilty a few weeks ago to criminal charges for rigging the bid, and her contract was terminated.

Gelbman set April 1 for the transfer of the 30 retired horses from Nanninga’s Abbottstown stables.

On the day of the move, Nanninga was alarmed over what she feared was the fate of some of the horses and called in the local SPCA to monitor the events.

She broke down in tears when the three horses were killed.

Officials at the SPCA in York County declined comment.

Calls to the vets at the scene, at Mason-Dixon Equine, were not returned.

Terry Smullen, owner of Smullen Farms in upstate Cobleskill, said she had been supposed to receive 15 horses but got only 13. Cara Cargill, owner of Willoughby Ridge Farms in Holderness, NH, said she also was supposed to receive 15 but got at least one fewer.

Both said their new arrivals were doing well.

murray.weiss@nypost.com

