A former American Humane Association employee filed a lawsuit against HBO and the AHA for covering up abuses to horses on the set of HBO's series "Luck," which was canceled in early 2012.

Barbara Casey, who worked as the director of production in the American Human Association's film and TV unit, claims that HBO and Stewart Productions, the producers of "Luck," wanted to save time and money and pressured the AHA to allow them to violate AHA's animal safety standards, reports The Hollywood Reporter.

"AHA bowed to political and financial pressure and refused to report the Production Defendants' conduct to the authorities," Casey alleges in the suit, according to THR. "AHA instructed Plaintiff not to report such conduct. AHA engaged in efforts to conceal and cover up the production defendants' criminal activities."

According to Casey, those conducts and criminal activities include drugging horses, using underweight and/or sick horses routinely for work on the show, misidentifying the horses so that animal safety representatives couldn't track their medical histories and more, according to the lawsuit filed in Los Angeles Superior Court cited by the publication.

HBO replied to the lawsuit today, stating: "We took every precaution to ensure that our horses were treated humanely and with the utmost care, exceeding every safeguard of all protocols and guidelines required of the production. Barbara Casey was not an employee of HBO, and any questions regarding her employment should be directed to the AHA."

Casey also sued the AHA for wrongful termination for firing her in January 2012 after 13 years with the organization.

The American Humane Association was in charge of investigating the deaths of three horses on the set of "Luck" over a period of 2 years.

HBO canceled production of the series "Luck" in March after the death of a third horse stirred outrage.

A third horse died in March after been euthanized following a serious head injury. The other two horses died during filming of Season 1 in 2010 and 2011 after being injured during racing scenes.

"While we maintained the highest safety standards possible, accidents unfortunately happen and it is impossible to guarantee they won't in the future. Accordingly, we have reached this difficult decision," HBO and the series' producers said at the time.

Animal activists suggested that the show's producers hid how they were treating the horses. People for the Ethical Treatment of Animals (PETA) said that HBO refused to tell them about the first two horses that died during filming of season 1.

PETA said that it learnt from "caring whistleblowers" that allegedly one of those horses hadn't raced in months and was so sore that it had to be drugged with a potent cocktail of muscle relaxant and anti-inflammatory and painkilling drugs. They said the other horse had not raced in nearly four years and was arthritic.

"Both horses were 'raced' twice in one day - something even fit thoroughbreds would never be subjected to," PETA said in a statement. "Both horses on the set of Luck broke down after the second run. Their leg fractures were so violent that their bones shattered under the pressure."HBO has not addressed the claims publicly."

Dr. Rick Arthur, the equine medical director for the California Horse Racing Board, told the New York Times that it was "absolutely irresponsible" to suggest that the first horse "had drugs in it before it was filmed," and that they were given "in response to the injury."