A winning treble by trainer Neville Parnham was marred when his two-year-old barrier trials star Forty Thieves died in a postrace tragedy at Belmont Park on Wednesday.

Forty Thieves, on his first day at the races, collapsed with a heart condition as sweat was washed from him in a hosing bay at the track’s stabling area.

On-course veterinarians and stewards rushed to the valuable colt, but he could not be saved.

A brilliant winner of two Belmont barriers trials, he finished last in Wednesday’s Crown Perth Plate (1200m) after leading clearly to the 250m post.

“Sadly, he appears to have ruptured his aorta,” WA Racing Hall of Fame trainer Parnham said. “Forty Thieves was a lovely youngster and I really liked him. This is an emotional blow to our stable.

“Forty Thieves ran up his breeding in trials wins and he showed signs of a very bright future.”

Forty Thieves, raced by WA owner Santo Guagliardo, was a grandson of the late Bart Cummings’ dual Cox Plate winning stallion So You Think and former Perth carnival star mare Ellicorsam.

Parnham won the Crown Perth Plate with Diamond Command, who had been rated as his second-stringer to Forty Thieves.

Closing on a career total of 2100 wins, Parnham bought Diamond Command online for $1750.

“I liked the filly’s breeding,” he said. “She could not have been more impressive in her race debut today.”

Diamond Command, by Parnham’s WA Guineas winner Rommel, is from a daughter of great galloper Lonhro.

The trainer’s other winners on Wednesday were War Gem, a $170,000 yearling purchase, and Ghost Who Walks.

Meanwhile, former jockey Felicity Forbes-Ives, 35, trained her first city winner when six-year-old Forty Niner scored in a 1200m maiden on Wednesday.

“I won four races as a jockey on Forty Niner’s dam Infinite Star,” Forbes-Ives said. “But a series of injuries have hampered Forty Niner and today he’s finally got his first win, at his 11th start.

“His setbacks have included a head injury in the barrier at trials and a fractured knee. He’s often been on the verge of retirement.”

Forbes-Ives, who finished race riding several years ago, trains only one or two horses.

Trainer Lindsey Smith says his WA stable star God Has Chosen has improved ahead of Saturday’s $200,000 Hyperion Stakes (1600m) at Belmont.

The gelding notched a Belmont Sprint (1400m) win for jockey Clint Johnston-Porter last Saturday week.

“He’s come forward further,” Smith said on Wednesday. “After the Hyperion, he’ll tackle the Strickland Stakes.

“God Has Chosen will stay in Perth for Ascot’s Railway Stakes and Kingston Town Classic later this year.”