Dr. Thomas J. Lurito, a veterinarian who practices at Philadelphia Park, has been ruled off the grounds of the track while the racing commission investigates an incident in which the vet allegedly shot an injured filly in order to euthanize her, according to officials of the track and the trainer of the horse.\nThe injured filly, 4-year-old Rich and Mean, was allegedly shot by the veterinarian in her stall at Philadelphia approximately two weeks ago after attempts to repair an injured knee did not produce measurable results, according to Ralph Riviezzo, her trainer. Riviezzo said that he did not know that the veterinarian would use a firearm to euthanize the filly, and that he was not present when the filly was shot.\n"I didn't know how they were going to euthanize her," Riviezzo said on Tuesday. "I was away. I got a phone call the next day that said that they put her down that way. One might argue how humane that is, but I will not get into that argument."\nThough gunshot is considered an acceptable and humane method for euthanizing horses under standards developed by equine veterinarians, horses at racetracks and medical facilities are typically euthanized with an injection first of a sedative and then an injection of barbiturates - usually, sodium pentobarbital - to induce cardiac arrest. \nRiviezzo declined to identify the veterinarian. Chris Ryder, a spokesman for the state racing commission, confirmed that the veterinarian was Dr. Lurito. Ryder also confirmed that Lurito has been ruled off the grounds at Philadelphia Park until the investigation is complete.\nReached by telephone on Tuesday, Lurito said he would not comment on the incident.\nMike Melendez, a steward at Philadelphia Park, also would not comment other than to confirm that the incident was under investigation.\nRyder would not provide additional details about the investigation, other than to confirm that the investigation involved the allegation that a horse was shot by a veterinarian who had been hired to euthanize her.\n"At this point, we are not able to make any additional comments until the investigation is complete," Ryder said.\nRiviezzo said that it was his understanding that Lurito was ruled off the grounds for having a firearm at the racetrack. \nRich and Mean, a 4-year-old daughter of Distinctive Pro, last raced on May 24, finishing eighth of nine in a six-furlong maiden claiming race for a price of $10,500. Riviezzo said that she injured her knee in that race, but that he could not recall the exact date that she was put down. Rich and Mean had raced six times in her career, and had failed to hit the board in all six of those starts.