Ledgers Dream falls at Morphettville. © Coalition for the Protection of Racehorses
The latest death was Ledgers Dream, racing at Adelaide's Morphettville Racecourse, in South Australia, in the Dominant Hurdle, over 3100 metres.
Ledgers Dream appeared to collapse at a hurdle along the back stretch, making no apparent attempt to lift as he approached the jump, and then tumbled over the obstacle.
The cause of death is expected to be known today.
One report suggested the 10-year-old racehorse broke his neck when hitting the ground.
Jockey Marty Kelly escaped injury.
The death of Ledgers Dream is the sixth this season across South Australia and Victoria, the only two states which still have the sport.
Animals Australia, which has branded the sport cruel and dangerous, listed the horses who have died in the first weeks of the 2011 season - Casa Boy, Hammerblow, Squire Rex, Java Star, Shine The Armour and Ledgers Dream.
Horses were dying at a rate of a one a week so far this season, the group pointed out.
"It's 10-20 times more dangerous to horses than flat racing, and many of the injuries sustained during jumps races can be horrific."
Racing Victoria temporarily suspended jumps racing after three jumps horses died during the Warrnambool racing carnival in May 2009.
The season was allowed to resume after new conditions were imposed.
Animals Australia noted that the jumps death rate the industry is trying to stay below was still 15 times that of flat rating.
It said as long as the Victorian and South Australian governments and racing industry leaders permit jumps racing to continue, they share the responsibility for every horse dying on the track.