"Auckland’s biggest 'PARTY' is a disgrace and a celebration of animal abuse," CPR wrote in a statement.

"Glamming up doesn't justify supporting animal cruelty. We want people to think twice about attending and supporting racing events."

There were 17 recorded deaths in the racing industry in the 2018/19 season according to NZ Thoroughbred Racing (NZTR), but CPR says true toll is closer to 2500 - a figure NZTR has disputed.

CPR spokesperson Aya Oba said the deaths came through "haemorrhages, cardiac arrest and other injuries caused from being forced to race".

"There are many more hidden behind the scenes," said Oba. "It is standard practice that when the horses are no longer profitable, many will be sent to the knackery. All of these deaths are for gambling profits and entertainment."

But NZ Thoroughbred Racing (NZTR) manager of racing and equine welfare Martin Burns told Newshub on Monday New Zealand has one of the lowest horse racing death rates of anywhere in the world.

"We are constantly assessing our tracks and training methods to ensure the risk of fatal injuries is minimised. Unfortunately, we do not live in a perfect world and all accidents are not preventable. When they do happen, they leave a devastating impact on those close to the horse."

Burns said horses "are exhibiting natural behaviour" when they race.

"There must be a willingness to compete from the horse - if that is absent there is nothing a 50kg jockey is going to be able to do to make a 500kg horse gallop."

He said the claim of 2500 deaths a year "seems to be a figure plucked from the air", as only 4800 horses start races in New Zealand each season. Around 3300 are born annually, which about half sent overseas.

"If we were losing 2500 horses annually it would soon be apparent."

NZTR told Newshub CPR failed to make a submission when it was updating its welfare guidelines, so couldn't be taken seriously.

Protesters will gather at Ellerslie Racecourse from 11am.