A 62-year-old man was driving the horse-drawn carriage on a dirt road beside the river heading toward Sevelin when several dogs appeared around 1.30pm, cantonal police said in a news release.
The dogs were well behaved and were led away by their owners from the road but they appeared to have frightened the horse, the release said.
The animal tried to turn around and it stumbled backwards down an embankment, dragging the carriage with it into the water, police said.
The driver was able to jump from the carriage and extricated the horse from the carriage.
The animals managed to reach a sandbank and was led back to the road.
Suffering from minor injuries, the horse was examined by a veterinarian and appeared to be otherwise none the worse for wear.
Police released a photo of the carriage, submerged upside down in the Rhine.
It was finally retrieved by a towing service.