A 25-year-old man is fighting for his life after he was injured at the 2019 Normanton Rodeo in northwestern Queensland.

The man sustained a critical head injury in an altercation with an animal at the rodeo, believed to have been a bull, around 2:10pm Sunday afternoon.

He was transported to Normanton Hospital, 40 kilometres inland from the Gulf of Carpentaria, before the Royal Flying Doctors arrived to fly him to Townsville Hospital.

A Hospital spokeswoman confirmed the man was in a critical condition.

In 2018, two bulls were injured and then had to be euthanised in front of hundreds of spectators at a rodeo event in Brisbane's north, prompting planned protests in April about the ethics of the sport.

Animal Liberation Queensland (ALQ), rodeo campaign director Gayle D'Arcy said animal behaviourists classed bulls as prey animals who felt they were under attack when they had a rider on their back, spurs sticking into their shoulders and a flank strap around their belly.

"We're told, putting that all together, the animal feels like it's under predator attack and instinctive," she said.

"I they weren't frustrated frightened or panicked then they wouldn't do the excessive bucking.

"It's really exploiting their fear instincts for people's entertainment."

RSPCA Australia said it was "strongly opposed" to rodeos because of the potential for significant injury, suffering, distress or death of animals involved.

The deaths at last year's event at Eatons Hill in Brisbane prompted RSPCA chief executive Mark Townend to attack rodeo spectators, saying: "I believe we are breeding a bogan society with people getting thrills out of seeing animals killed, maimed or injured all under the ¬banner of entertainment or sport."