A steeplechase event was abandoned mid-race at Sandown on Wednesday after a horse crashed through an obstacle and had to be euthanised.

The race was called off as the field approached the home straight because Show Dancer, which came to grief at a fence early in the race, lay stricken on the turf.

Show Dancer's hind legs appeared to slip as he readied himself to take off for the jump, sending him through the fence, flipping and throwing his rider.

Show Dancer, the winner of three races, was euthanised.

His jockey Martin Kelly and two other riders who came off their mounts during the event escaped serious injury.

Racing Victoria steward Rob Montgomery said he had no option but to abandon the race because Show Dancer was inside the line of the jump on the ground and could have impeded the remaining horses in the race.

Montgomery spoke to jumps jockeys before the running of the second race, a maiden hurdle, and asked if they had any safety concerns after the Show Dancer incident.

"It does appear the horse's hind quarter slipped going into the fence," Montgomery said.

The jumps jockeys were all happy to keep riding.

"Safety is paramount to us. I'll call the thing straight off," Montgomery told the riders.

Kelly, the rider of Show Dancer, returned to the jockeys' room with both arms bandaged.

"The sport has significantly improved its safety record during the past four seasons with a 60 per cent reduction in the fatality rate. Today serves as a reminder that we cannot rest on our laurels," Racing Victoria's Paul Bloodworth said.