State police are investigating, but no arrests have been made since Wild Eyed and Wicked and the four others each developed a severely swollen front leg more than a week ago at the Double D Ranch.
While the infections now appear to be under control, a ranch representative had said early on that the horses would be lucky to survive.
Owners and breeders struggled with the idea that such brutality had invaded their well-mannered community, where the high-stepping, muscular horses with long, arched necks are judged for their distinctive walking styles in divisions such as fine harness, park and country pleasure.
"Our best friends are our biggest competitors," Milwaukee breeder and shower Scott Matton said. "You go and fight and battle the best you can, but sabotaging somebody else's horse? I've never seen that. We are competitors, but we have to buy horses from them and they have to buy horses from us. We have to get along."
Bridget Parker, a business associate of Double D Ranch owners Dave and Dena Lopez, said investigators have told her that they had never heard of a similar case.
The horses - the others are Cats Don't Dance, Meet Prince Charming, Kiss Me and Sassational - were in their stalls at the ranch in nearby Versailles when the injuries were discovered June 30.
Each horse had a nearly identical circular wound on the back of its left front pastern, the short bone between the hoof and ankle.
All but Sassational were supposed to compete this week in the Lexington Junior League Horse Show at The Red Mile, an event in the breed's Triple Crown. The injured horses were instead at home at the Double D, under the care of veterinarians.
The most severely ill is 11-year-old gelding Wild Eyed and Wicked, who won the saddlebred Triple Crown in 2000 and 2001.
Carol McLeod, who is helping treat the animals, says the horses appeared to be improving. The horses are wearing special shoes and have casts on their legs to support the tendons, and they have also spent time in an oxygen chamber.
"I'm maintaining a level of cautious optimism," McLeod said. "We are in it for the long haul."
But the World's Championship Horse Show in Louisville next month is out of the question, Parker said. "It's a career-ending injury unless we're damn lucky," she said last week.
Blood and tissue samples were being tested to try to identify the substance injected.
"Nobody in their wildest dreams would ever imagine something like this happening in our industry," said Dede Gatlin, advertising manager for the Lexington-based American Saddlebred Horse Association. "This is something that families do together."
By Murray Evans