The front window of Nataliya Couture on London Road was smashed after an incident with four horses and a carriage.
Shards of glass, manure and blood could be seen around the shop window and the pavement below.
A taxi driver who saw what happened said one horse looked particularly injured.
Mohamed Amjad said the carriage was coming down the road, claiming the horses may have been panicked by a horn blowing.
He claimed the front two horses “slid” into the shop front.
He said: “People put towels on to try and control the blood.”
Racegoers in attendance on Ladies Day at Royal Ascot. June 21, 2018
It is not thought anyone was injured in the incident on Thursday evening as racegoers were leaving Ascot.
The shop sells formal wear much like that showcased by many of the women in attendance on Ladies’ Day.