“C’mon, big boy!”

Bill Kaplan rises to his feet as the field of horses turns into the stretch. It is the second race at Calder Casino & Race Course, a nondescript claiming race on a lazy Sunday.

There are no more than a handful of fans seated in the second-floor grandstand, and even if the horse could understand what his trainer was saying, he can’t hear him. The grandstand is enclosed by glass.

That doesn’t stop the trainer.

“Dig in,” Kaplan exclaims, encouraging his horse, Preponderate, in the final strides.

But it does no good. Preponderate loses by a neck.

What few fans there are discard their losing tickets and turn the page in the program to do their homework on the next race.

These are the dog days of horse racing in South Florida and, for the first time ever, Calder isn’t the only game in town.

About eight miles due east, Gulfstream Park is also running.

And based on the early returns, winning the battle for fans and their money.

Even though the two tracks carded eight-race programs of equal quality Sunday, more than twice as much money was wagered on Gulfstream’s races ($2.1 million) than on Calder’s (about $973,000).

Long content with being a “winter” track, Gulfstream, for the first time since its opening in 1939, is racing in the summer on a weekends-only basis.

Most of the summer horse population in South Florida is stabled at Calder.

To entice Calder’s horsemen, Gulfstream is dangling a bigger carrot in the form of higher purses. On Sunday, Gulfstream paid out $167,000 in purses compared with the $116,000 in purses offered at Calder.

Calder has countered by restricting many of its horses from racing at Gulfstream. The potential penalty: A Calder horse that races at Gulfstream might not be allowed back on the grounds.

As a result, some trainers are moving their stables from Calder to Gulfstream, which has no such restriction. Hundreds of horses have already made the move, and more are expected to do so.

Trainers say they are caught in the middle.

“There just aren’t enough horses to support head-to-head competition,” Kaplan said. “I can’t see them going all summer running head to head. I don’t think it’s possible.”

Neither track’s racing cards Sunday were what most bettors would consider attractive. Small fields were the norm. Not a single race at either track featured as many as nine horses. A total of only 50 horses raced Sunday at Gulfstream. The number was only marginally better at Calder: 55.

Executives for the tracks are pointing fingers at one another.

Calder vice president John Marshall said the whole mess could have been averted had Gulfstream not acted in “bad faith” during recent negotiations to solve the issue.

Marshall said Calder was willing to condense its meet to 40 racing dates — exactly enough to keep its casino license — until the deal collapsed at the last minute because horsemen weren’t privy to a new purse arrangement.

Gulfstream president Tim Ritvo scoffed at that Sunday.

Ritvo said Gulfstream’s offers to Calder — one to purchase the other track outright and the other to lease its dates — were so lucrative that “we thought they’d be drinking champagne in Kentucky.”

Calder is owned by Louisville-based Churchill Downs.

Ritvo said Gulfstream offered to pay Calder a yearly amount that was more than what the track had been making.

“It was a good deal for them,” Ritvo said. “What it came down to was making them whole. The difference was in their version of making them whole and our version.”

Ritvo said Calder demanded that Gulfstream pay its taxes, insurance and maintenance on the building — demands that Gulfstream refused.

And so the two tracks, once allies in South Florida racing, are at war.

Said Howie Tesher, another longtime trainer, of the two thoroughbred tracks duking it out: “It’s like two drunks standing outside arguing with each other, and they’re both ready to fall down. It’s an embarrassment that this should happen.”