The footage of a calf turning its horns to a matador's capes as it coughs up blood has shocked even defenders of the country's long-running tradition.
Just recently separated from its mother, the animal presented no real threat to bullfighters in the ring but was killed for entertainment as part of a festival in the town of Valmojado outside Madrid.
Now Spanish citizens have joined the voices of the animal rights political party who released the film from the Castilla-La Mancha region by condemning the game.
"What is worse is all the clapping and people bringing their children up to see this 'culture festival,'" wrote one Facebook user, Fido Miguelon.
"Culture is reading books, not killing a defenceless animal."
The calf is taunted with a brightly coloured cape by young men who pierce it from the shoulder blades through its body with long, thin swords or darts. The animal can be seen hopping and jumping with the point of the blade coming out through the stomach.
After the men pin it down by the horns and appear to cut off its fur or flesh, the calf begins to fall over and choke up blood. At the end of the footage the young men kill the animal with a knife.
Animal rights political party PACMA, which stands for the Animalist Party Against the Mistreatment of Animals, shared the footage this month after winning a record number of seats at the Spanish general election in July.
Founded 13 years ago, PACMA won 285,000 votes off the back of a campaign which has banning bullfighting at its heart, according to Spanish news site The Olive Press.
And now an anti-bullfighting demonstration on 10 September is expected to draw tens of thousands of protesters in one of the largest shows of anger against the sport in the country to date.
"It is sad to see how this poor animal, a baby animal in this case, is slowly dying without being able to enjoy their life," said another Facebook user, Nacho Castro Lobo.
"I say NO to animal abuse."
One commentator put it: "This is mentally ill - whoever pays and and enjoys watching this has a very big problem in the head. Heartless a********s."
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