Hamilton's evening meeting was abandoned after race three following an "unprecedented level of rain".
Racing at the Scottish track got under way on ground described as good to soft.
But heavy rain had already set in, and conditions deteriorated significantly - resulting in an inspection after the 6.50 race, which concluded that conditions were unsafe to continue.
Hamilton course manager Sulekha Varma told Racing TV there had been "an unprecedented level of rain this evening".
Earlier on, Vincent Ho rode his third winner of the week in Scotland when Good Night Mr Tom took the opening BB Food Service Nursery Handicap.
The Hong Kong-based jockey is in the UK during the HK close season and rode winners earlier in the week at Ayr and Musselburgh.
He said: “There is nothing like Hamilton back home and I ran around the track to get to know it beforehand. The straight has the dip and the uphill climb while the tracks are much flatter in Hong Kong.”
Highflying apprentice Sean Davis was successful on Bedtime Bella in the Boe Violet Gin Novice Stakes.
"I could get across to the stands side as much as I would have like so she’s done it well in the end," Davis said.
"The form of her second in a claimer at Catterick is working out nicely."
Cale Lane, who is currently in foal, landed the Gas Call Services Silk Series Lady Riders Handicap under locally-born Paula Muir on the mare’s final appearance on a racecourse.
The race, the third, was run in a thunderstorm and the remainder of the seven-race card was abandoned.
