LONDON — Irish jockey Robbie Dunne was given an 18-month suspension on Thursday after being found guilty of bullying and harassing female rider Bryony Frost in a disciplinary case that highlighted a weighing-room culture described as “not conducive to the development of modern-day race-riding.”

Dunne was found in breach on four counts of conduct prejudicial to horse racing by an independent three-person disciplinary panel of the British Horseracing Authority, which looked into evidence of his behavior toward Frost.

Dunne was charged with seven breaches in total. The other three, of violent and threatening behavior, are yet to be considered.

Three months of his 18-month ban are suspended.

The majority of the incidents in question took place in 2020, when Dunne was found by the panel to have used threatening and misogynistic language toward Frost, who is from England.

“Our conclusion on the whole of the evidence,” said Brian Barker, who chaired the panel, “is that a course of deliberate conduct over a significant period of time has been revealed. This has progressed from distasteful targeting to deliberate harassment on and off the course and onwards to occasional cases of dangerous bullying.”

Barker said Frost had broken the “code” of the weighing room by taking her complaint to authorities, “knowing that her isolation — and rejection by some — was inevitable.”

Barker described the language used toward Frost as “totally unacceptable, whatever the frustrations about her style and whatever the habits of the weighing room.”

“Secondly,” he added, “in reviewing the evidence given and their approach, by jockeys of repute, as well as by the valets — who probably find themselves in a difficult position — we have a real concern that what was referred to … as ‘the weighing-room culture’ is deep-rooted and coercive and that in itself is not conducive to the development of modern-day race-riding.”

Dunne had denied the four charges of conduct prejudicial to horse racing and two of the three counts of violent or improper behavior.

Frost is regarded as a trailblazer in British and Irish horse racing. In 2019, she became the first female jockey to win a top-grade race over obstacles at the prestigious Cheltenham Festival.

“I would like to thank every individual including the racing public that has supported me not only during the last couple of weeks but throughout,” she said in a statement on Thursday. “I wish now to take a few days to reflect on the outcome before I make any further comment.”