How serious is grabbing a quarter?

[Stickhorse]

I find it very interesting the difference of opinion on just how serious an injury a grabbed quarter is to a horse in a race.

I just heard Richie Migliore comment on California Chrome's grabbed quarter, "His adrenaline was flowing. Horses are just so tough; I doubt he really even felt it."

Then this from Billy Gowan in the Orange County Register.

Rival trainer Billy Gowan, whose Ride On Curlin did not finish the Belmont, compared the injury to a human ripping off a fingernail and said it is extremely painful for a horse.

Many horses, he said, will pull up and not finish the race.

“He’s a pretty courageous horse to finish fourth,” Gowan said.

I'm a fan and handicapper and don't have the experiences of Mr. Migliore or Mr Gowan. I was wondering what others know about the severity of this injury . I'm guessing is that we probably will never know.