Dustin Hoffman

HBO has ended production on Luck effective immediately following the death of three horses, the pay cable channel announced Wednesday.

"It is with heartbreak that executive producers David Milch and Michael Mann together with HBO have decided to cease all future production on the series Luck," the network said in a statement.

"We maintained the highest safety standards throughout production, higher in fact than any protocols existing in horseracing anywhere with many fewer incidents than occur in racing or than befall horses normally in barns at night or pastures.  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 suspends use of horses on Luck

Two horses died during the filming of Season 1, which took place last year. After a third horse died Tuesday during production on Season 2, the network announced that all use of horses on the show would be suspended indefinitely. In a statement on its site, PETA said it had "sent a complaint to Los Angeles law enforcement urging the agency to investigate the deaths of two horses during the filming of the first season."

Filming had already begun on Season 2, with Revenge's Margarita Levieva set to join the cast. The most recent casting call sent out was for the second episode of Season 2, and it is not yet unclear how many episodes were completed before production shut down. Luck's first season consisted of nine episodes. Season 2 would have run for 10 episodes. A show rep could not be immediately reached.

Is HBO's horse-racing series Luck a big gamble?

"The two of us loved this series, loved the cast, crew and writers," Mann and Milch said in a statement. "This has been a tremendous collaboration and one that we plan to continue in the future."

Luck, starring Dustin Hoffman, launched in January to much acclaim. The show premiered to 1.1 million viewers, and quickly earned a Season 2 renewal, before dropping to 501,000 viewers a month later for the Feb. 26 episode, according to Vulture.