The premiere episode of the HBO series Luck aired without a disclaimer that no animals were harmed in production, as life tragically imitated art on two separate occasions: While filming the pilot episode -- which included a dramatization of a downed racehourse -- a real life horse was euthanized after suffering a serious fracture during a racing scene.

Only after a second horse was put down because of an injury (during the filming of the seventh episode) did HBO reconsider the safety protocols for animals used in the gritty one-hour drama about thoroughbred racing.

People for the Ethical Treatment of Animals (PETA) is up in arms and demanding answers from HBO.  A late January report on the PETA's web site claims that the animal right advocacy group had attempted to communicate with HBO about the show's safety measures prior to the start of production.

PETA repeatedly reached out to series creator David Milch and others associated with the HBO production before shooting began, but our efforts were rebuffed, wrote PETA's Jennifer O'Connor.

Perhaps if producers had considered the proved safety protocols that we would have suggested, these horses would still be alive...two dead horses in a handful of episodes exemplify the dark side of using animals in television, movies, and ads.

Kathy Guillermo, vice president of PETA, told Entertainment Weekly that HBO was less than receptive to their questions after the horse deaths were reported.

We asked for the names of the horses, whether they were retired racing horses and what their records had been, what physical condition they were in, what their rest periods were, and if they were checked between racing sequences, Guillermo said. When we began to ask uncomfortable questions, they closed the door on us. We received an email this morning saying all this information is confidential and that they're doing all that they can to prevent injuries.

The American Humane Association, which monitors animal safety in film and television productions, reported the incidents in a statement published on its website Jan. 27.

During the filming of the new HBO series, Luck, two fatal accidents occurred several months apart - one during the filming of the pilot and one during the filming of the seventh episode. The two racehorses stumbled and fell during short racing sequences. The horses were checked immediately afterwards by the onsite veterinarians and in each case a severe fracture deemed the condition inoperable. The decision was that the most humane course of action was euthanasia.

 An American Humane Certified Animal Safety Representative was monitoring the animal action on the set when the incidents occurred and observed the veterinarian on the set perform the soundness checks and approve the horses, prior to racing them. A full investigation and necropsy was conducted for each accident immediately afterwards.

 Throughout the series there are numerous racing sequences as well as milder action with horses in barns, being walked, groomed, bathed, etc., the statement continues.

The extraordinary amount of horse work incorporated in this plotline called for several American Humane Association Certified Animal Safety Representatives to ensure that all guidelines were met, including the additional precautions, and all the animal action was monitored.

In a statement to the New York Observer, HBO described the changes in the safety protocols after the animal deaths.

After the second accident, production was suspended while the production worked with AHA and racing industry experts to adopt additional protocols specifically for horse racing sequences. The protocols included but were not limited to the hiring of an additional veterinarian and radiography of the legs of all horses being used by the production. HBO fully adopted all of AHA's rigorous safety guidelines before production resumed.

PETA has launched a petition via Care2 to convince the producers of 'Luck' to comply with PETA's suggestions [for safety measures] and present future casualties on set.

The petition has received 7,592 signatures -- nearing its goal of 10,000 -- as of Wednesday afternoon.