Thoroughbred horse breeding is an instance where Ireland can claim to be among the world's best, but Brexit is giving the industry huge cause for concern.

Uncertainty over the future arrangements for exporting horses to Britain, its main market, has sparked frustration and anger in a sector worth more than 1.8 billion euros ($2.1 billion) to the economy, and which supports almost 30,000 jobs.

"It is a huge employer in the countryside, so anything that damages it is something to be really worried about," said Harry McCalmont, whose Norelands Stud is a prominent middle market breeder.

Talk of Brexit dominated last week's foal and breeding stock sales at Goffs, Ireland's premier public auction house, where buyers from across the world spent 41 million euros.

The tone was set by a foal by star Irish-based stallion Galileo, which sparked a bidding war before the auctioneer's gavel finally fell at the princely sum of 1.1 million euros to an agent acting for an unnamed US buyer.