KENNETT SQUARE — Barbaro's perilous road to recovery has suffered its biggest setback yet.

The Kentucky Derby winner faces major problems for the first time since surgery to repair the right hind leg he shattered in the Preakness seven weeks ago. And the colt's veterinarian said Monday "we're in tough times right now."

Barbaro had a new cast applied for a sixth time — the fourth change in a week. The latest development followed three hours of surgery Saturday night when doctors replaced the titanium plate and many screws and also treated an infection.

Dr. Dean Richardson, the chief surgeon at the New Bolton Center, looked haggard during the briefing, and said it took more than 15 hours from the start of Saturday's surgery until Barbaro had fully recovered from anesthesia.