A US TV drama set in the world of American horse racing has been cancelled after a third horse died during filming.

The network HBO stopped filming Luck, which stars Dustin Hoffman and Nick Nolte, when the incident happened on Tuesday (13 March) during the making of a second series.

“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,” HBO 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.

Accidents unfortunately happen and it is impossible to guarantee they won’t in the future. Accordingly, we have reached this difficult decision.”

The deaths happened several months apart – one during the filming of a pilot episode and the second during the filming of the seventh show.

The third death took place on Tuesday, when a mare that was being led reared and went over, suffering a head injury.

The American Humane Association (AHA) issued an order the same day, suspending the use of horses in the show, pending a “thorough and comprehensive investigation”.

And HBO cancelled the series yesterday.