A young jockey has been banned from racing for two weeks for hitting his horse before a race in Port Lincoln on South Australia's Eyre Peninsula.

Dylan Caboche, 22, was behind the barriers trying to steady the horse, She's Reneldasgirl, on Wednesday when he dismounted and punched the animal.

"Caboche was observed striking She's Reneldasgirl in the area of its girth as the field was being loaded into the starting gates," Thoroughbred Racing SA (TRSA) said in a statement.

The horse went on to finish eighth in a field of 10.

After an "immediate inquiry", stewards suspended the apprentice jockey for two weeks, under a rule relating to misconduct.

"TRSA does not condone and will not tolerate such behaviour," the racing authority said.

TRSA suspended jockey Dylan Caboche for two weeks, but said he had the right to appeal. ( TRSA )

RSPCA state chief executive officer Paul Stevenson said he was "appalled" by the jockey's actions, and described the two-week licence suspension as a "token" punishment.

"Given what it's saying about what is acceptable behaviour within the industry, it just isn't anywhere near sufficient," he said.

"Obviously the jockey just lost his temper, but that's just not acceptable from a professional sportsman."

But TRSA defended its response, saying it would act as a deterrent to other jockeys.

"It is hoped this penalty — which will remain on the rider's record and will impact his earning ability — will send a strong signal to others."

TRSA said Caboche's suspension begins on November 17, but said he had the right to appeal.

The RSPCA said it would seek legal advice on whether animal welfare laws had been breached.

Caboche recently brought up his 100th career victory.