The Central Park carriage horse that dropped dead on a Manhattan street suffered from a small tumor that likely led to a deadly aortic rupture, the union representing carriage drivers said Friday.

The horse, named Lady, crumpled to the ground in Hell’s Kitchen — just a block away from her stable — after she had only done two rides Tuesday afternoon, stoking renewed outrage from animal rights activists.

The preliminary results from the necropsy indicate the 15-year-old horse had a small tumor in her adrenal gland that likely caused an aortic rupture, according to a statement from TWU Local 100.

Lady the carriage horse dropped dead on a Hell’s Kitchen street in Manhattan on Tuesday afternoon, stoking renewed outrage from animal rights activists. Obtained by the NY Post

“This was a tragic and sad loss, and we are all mourning Lady’s death,” a statement from the union said.

“However, at least we now have some answers. The reality is that this sudden-death medical episode would kill a horse anywhere — in a field, park, stable, trail, or street — at any time.”

Cornell University College of Veterinary Medicine confirmed staff performed the examination Wednesday, but declined to provide further details.

The union also slammed animal rights “extremists” for stirring anger over the sudden death. 

“They repeatedly demonize blue-collar carriage-horse drivers, many of whom chose their line of work because they love animals and want to spend their days with them,” the union said. 

Lady had just started giving rides in the Big Apple after arriving in June from Pennsylvania after she was sold at an auction, TWU Local 100 said.

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The union also insisted she underwent a city-mandated physical that didn’t raise any medical red flags.

“There was zero wrongdoing or negligence here,” said Dr. Gabriel Cook, Lady’s veterinarian, through the union. Cook was not involved with necropsy.

But NYCLASS, an animal advocacy group opposed to Central Park horses in the city, hit back at the carriage drivers.

Edita Birnkrant, NYCLASS director, argued tumors “don’t appear overnight” and claimed the mass should have been caught sooner.

The preliminary results from a necropsy indicate the 15-year-old horse had a small tumor in her adrenal gland that likely caused an aortic rupture. Obtained by the NY Post

“This is a systemic failure, where horses are cleared without any comprehensive exams or blood work, then rubber-stamped by [the Department of Health] to be thrown onto chaotic city streets,” she said.

The average lifespan of a horse is roughly 25-30 years.

The city’s Health Department, which oversees carriage horses, said in a statement it will review the veterinarian interim report, in addition to other findings and lab results as part of its probe.

Protesters rallying in New York City to advocate for Ryder’s Law to phase out horse-drawn carriages, following the death of Lady. SARAH YENESEL/EPA/Shutterstock

PETA spokesperson Ashley Byrne said the latest development shows horses in the city aren’t getting appropriate medical treatment and the city is too easy on Central Park carriage drivers.

“Every time a horse drops dead or falls in the street from sickness or exhaustion, the drivers and their representatives all act shocked, that they can’t believe that it happened,” she argued. “And yet it happens over and over and over again.”

Lady’s tragic demise came almost three years to the day after another city horse named Ryder fell and later had to be put down, spurring a proposed ban on horse carriages in Central Park and a criminal indictment against his driver Ian McKeever.

McKeever was found not guilty of animal abuse charges in the death of the horse earlier this summer. The proposed ban introduced in the City Council has stalled. 

Additional reporting by Steven Vago.