Tragedy strikes the production of HBO’s “The Gilded Age”.

The network announced the death of a horse on the set of the show which they attribute most likely to “natural causes”.

“HBO was saddened to learn that on June 28, during filming on the set of ‘The Gilded Age’, a horse collapsed and died, likely of natural causes, according to a veterinarian’s preliminary findings,” HBO said in a statement, via The Wrap. “The safety and well-being of animals on all our productions is a top priority, and the producers of ‘The Gilded Age’ work with American Humane to ensure full compliance with all safety precautions. Following AHA’s recommendation, the horse was transported to a facility for a full necropsy. AHA has interviewed all involved personnel, and full necropsy results are pending.”

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According to someone with knowledge of the situation, the horse was 22 years old and was not new to filming. Production for the day wrapped after the horse collapsed and attempts were made to assist the animal.

PETA has responded to the news with outrage

“We’re calling on HBO to confirm the death, to conduct an immediate internal investigation into the incident, and to hold the party or parties who allowed it to occur responsible,” Courtney Penley, coordinator for animals in film & television for PETA, said in a letter to HBO Chief Content Officer Casey Bloys. “Finally, we’re asking you to take measures so that something similar never happens again.”

This isn’t the first time horses have died on set for an HBO production.

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In 2012, three horses died while the racing drama “Luck” was filming. The show was cancelled after one season after news of the deaths broke out. The letter also referenced this incident, calling out the company’s track record.

“These animals were unfit, arthritic, drugged, and pushed beyond their capabilities,” she continued. “Many weren’t accustomed to film sets and had received no training but were retired racehorses. We had hoped HBO might have learned something from that experience: namely, that horses aren’t props. They’re sensitive animals who can be startled easily, and they must be gradually accustomed to the changing conditions on a set.”