A grey hound trainer was attacked by a gang armed with baseball bats.
Detectives say the victim, from Wakefield, was deliberately targeted.
He was on his way to catch a ferry to Ireland to buy two dogs for a “substantial amount” of money.
He was driving along Liley Lane in Grange Moor at around 5.30am on Thursday when a dark coloured Volkswagen Golf overtook him and forced him to pull over.
Three men ordered the victim to get out of his car and hand over the money.
Det Con Richard Brooke said: “This would appear to be a targeted attack. The victim had been to greyhound stadiums in South Yorkshire before the incident and mentioned to people that he was going to Ireland to buy two dogs for a substantial amount of money.”
Two of the suspects were white and one was black.
All three were wearing dark clothes with hoods and scarves covering their faces.
They also stole a mobile phone, clothes and a set of keys before driving off in the direction of Kirkheaton.
Anyone with any information should contact police on 101 or Crimestoppers anonymously on 0800 555111.