A man convicted of setting off a fire extinguisher in the faces of two Clydesdale horses in a Rockhampton entertainment district has publicly apologised.

Giobi Geiger, 20, was dubbed "immature" in Rockhampton's Magistrates Court today over the incident on a Friday evening in January.

The court heard he had drank about 13 cans of rum on the night he was being driven around the city by a friend, Brandon Hohn.

"I was pretty out of it," Geiger told the court.

The 20-year-old said they were driving down Rockhampton's popular Quay Street when he found the fire extinguisher under the car's passenger seat.

He said he then decided to set it off outside the car window.

"I thought it would be something funny for the people to see," Geiger told the court.

Clopping past on a cart for tourists at that moment was Steve May, pulled by his two Clydesdale horses Kenny and Bailey.

"All of a sudden, there was a big 'woof' of a sound as the plume of white powder was discharged towards the faces of the horses," Mr May said.

"And then the car sped off."

Security footage from a nearby pub of the horses staggering through the smoke went viral on social media.

Video footage of the fire extinguisher attack on the horses went viral on social media. ( Supplied )

Geiger handed himself into police in the days after scathing comments about his actions appeared online and pressure from Mr Hohn.

Kenny and Bailey needed medical attention for mild conjunctivitis, however they were both back at work ferrying tourists on their cart the day after the attack.

Last week, Geiger pleaded guilty to two counts of animal assault and two associated charges.

However, his defence lawyer contested the facts, claiming that Geiger had not seen the horses before he set off the fire extinguisher and that he therefore did not intend to hurt them.

Taking the stand, Geiger reiterated that he "didn't recall" seeing the Clydesdales out of the car window.

"Like I said, I was intoxicated," he said.

Capricorn Carriages owner Steve May with one of his Clydesdale horses. ( Supplied: Capricorn Carriages )

However, under cross-examination, police prosecutor Julie Marsden put to Geiger that he had already admitted to "checking out" women standing at a nearby pub just prior to the assault on the horses.

"You weren't so drunk that you couldn't see the girls," Ms Marsden said.

"I put it to you that you did see the horses, [but] you're saying now that you didn't."

Horse attacker apologises for his actions

In sentencing today, Magistrate Phillipa Beckinsale said it was "most unlikely" that Geiger had just accidentally aimed the fire extinguisher's hose at the horses.

"It seems unlikely that he did not notice the vehicle in which he was travelling had slowed down behind a large carriage pulled by two large horses," she said.

Giobi Geiger apologised for his actions after the court case wrapped up. ( ABC News )

Magistrate Beckinsale sentenced him to 120 hours of community service and ordered him to pay more than $4,000 in fines and veterinary bills.

She added that Geiger was "extremely lucky that the horses had a calm temperament" and had not bucked during the attack or hurt others.

"[This was] the poor and silly decision by an immature young man," she concluded.

Afterwards, the cart's driver Mr May told the media that Bailey had developed a stress condition since the assault, however no evidence of this was tendered to court.

"It used to be a real pleasurable experience doing this but I've lost a little bit of that, I'm sorry to say," Mr May said.

Outside court, Geiger apologised and said he had learned a lesson about being "drunk" and "stupid".

"I really didn't want that to pan out like that," he said.

No criminal history was recorded.