A WATCHDOG is launching an investigation after four horses, including one trained in County Durham, died in one day at a racecourse.

Smart Ruler, Leather Belly, Sierra Oscar and Kensukes Kingdom were all fatally injured at Musselburgh on Monday.

Leather Belly was trained by Rebecca Menzies of Morden, near Sedgefield, pictured below.

The British Horseracing Authority (BHA) is now to review what may have led to the equines' deaths, with one seemingly related to a "sudden collapse".

The Northern Echo:

Speaking to the Northern Echo, Rebecca Menzies said: "It was very upsetting for the owners, the staff in the yard and myself to lose such a young and promising horse at Musselburgh. 

"The regulators are investigating the circumstances and we are awaiting their report."

Bill Farnsworth, Musselburgh Racecourse general manager, said: "Our thoughts are with the owners, trainers and stable staff of these horses.

"The ground conditions and weather at Musselburgh Racecourse on December 3 were ideal for racing but until we have further information it would be wrong to speculate as to the cause of these tragic incidents.

"We will work closely with the BHA and assist their investigation to establish what happened and to ensure that Musselburgh continues to adopt best practice for all participants in racing."

Having multiple deaths in a single day of racing has been described as "very rare" by the regulator, who said the fatality rate in Britain over the last few years has reduced to around 0.2% of runners.

Inspectors are due at the racecourse in the coming days.

Some of the horses are also being sent for post-mortems to establish more information.

Robin Mounsey, BHA head of media, added: "The incidents at Musselburgh were extremely distressing for everyone involved in the sport, not least for the owners of thehorses and the trainers and stable staff who cared for them through their lives.

"As the sport's independent regulator we obviously treat issues such as this very seriously and work will now be undertaken to identify if there are any risk factors at the course or with the horses that might have contributed to these incidents."