Early on a Saturday morning in October 2014, a 22-metre long, highly graphic billboard was unveiled above one of Melbourne’s busiest roads.

Strategically placed right in front of an advertisement for the upcoming Spring horse racing program, the billboard featured a dead horse lying on the ground along with the tagline, “Is the party really worth it?”.

Paid for by the Coalition for the Protection of Racehorses (CPR), a small Melbourne-based protest group formed in 2008, the billboard placement was nearly cancelled by the landowner the night before, and only lasted a few days before it was taken down for good.

The provocative sign was successful in sparking a heated debate surrounding the group’s issues with horse racing, but it also marked a turning point in CPR’s ongoing tactics.

This year, you won’t see any gory images depicting the cruelties of horse racing through any traditional advertising routes. CPR campaign director Elio Celotto says the group has given up on these methods, with billboard advertisers no longer willing to show the anti-racing message — “now they won’t even talk to us,” he says.

Instead, the CPR has turned its attention towards a guerrilla marketing campaign and some inventive methods to raise awareness of its concerns with horse racing, which centre on the treatment of horses throughout their lives as racing animals, especially the issue of “wastage”, which refers to when horses are put down when they are no longer financially lucrative.

“It gets harder and harder for us each year to get our message out there and get paid advertising up around town,” Celotto tells Crikey. “There are a lot of vested interests in them [advertisers] not doing anything that would make the racing industry angry, and we find ourselves in a position where we have to fight harder to get the message out there.

“The billboard companies don’t want to touch it and neither do the taxi-back advertisers, so we’ve had to resort to different means of getting the message across.”

[Keane: yes, I hate the Cup — and for damn good reason]

While commuters will have to trample over a series of ads for Sportsbet and the Melbourne Cup to reach their train at Southern Cross Station, they won’t have to glance at any billboards showing dead horses this year.

Instead, the CPR has been employing guerrilla-style methods including “Ripper”, a plastic horse travelling around Melbourne in a float draped with distressing images of suffering horses, banners hanging over busy streets, chalk messages on city sidewalks and projected signs onto Federation Square.

And, most effectively for the group, CPR has been focusing its efforts on social media, where the tide is already turning against the annual race that stops the nation. In recent years, it has become just as common to see Facebook statuses or Tweets condemning the Melbourne Cup as it is to see glamorous photos of drunk punters attending the event.

No longer does the CPR have to rely on stubborn advertisers to reach the masses, now all they have to do is produce a video and let it loose on social media. One of these videos, a 35-second post focusing on the three horses that have died during the Melbourne Cup race across the last three years, has now been viewed over 14,000 times and shared over 500 times.

“While it’s harder and harder for us to get our message out there, it’s easier and easier for people to find out the truth,” Celotto said. “The racing industry needs to spend tens of millions of dollars to get the numbers going to their event but we only need somebody to see something once or twice to really make them think.

“Anyone that claims to care about animals cannot watch the videos we’ve produced and then say it’s OK to go to the races. You either love horses or you love horse racing.”

According to Celotto, this new style of marketing and awareness raising is working, with declining attendance figures at the Melbourne Cup and Spring racing calendar as a whole.

Attendance at the race that stops a nation has dropped steadily over most of the last decade, falling from just over 110,000 in 2010 to barely more than 100,000 last year. Punters have also been less enthusiastic for other flagship events like the Caulfield Cup.

[Rundle: condemning the Cup is a moral atrocity]

“We think we’re getting our message across,” Celotto told Crikey. “The Melbourne Cup has been in decline now for the past eight years, and that’s the time we’ve been around for. Racing has certainly lost its shine as people become more and more aware of the reality of what is actually going on.”

To mark the Melbourne Cup tomorrow, the CPR will be holding a “picnic and protest” event at a park directly across from Flemington Racecourse, with an aim to peacefully inform punters of their concerns about horse racing, and to show them that they can have virtually the same day without being complicit in animal cruelty.

“Our job on the day is to make people think about the other side of the racing industry and to show them that you don’t need to support the racing industry to have a good time,” Celotto said. “It’s very difficult once you know all of that to forget it. If you actually care about horses and animals then it’s very difficult to unknow what you do know.”

While the horse-racing industry and gambling corporations pour millions into large-scale advertising campaigns around Melbourne and the rest of Australia, Coletto says his group’s grassroots, guerrilla tactics are slowly working to turn the public opinion against the sport.

“The racing industry can throw millions of dollars towards promoting horse racing and they’ll get a lot of people there, but a percentage of those people will find out the truth of it and not return.”