According to state reports completed by racetrack veterinarians, nine greyhounds suffered broken legs at Massachusetts dog tracks during the month of May, bringing to 820 the total number of dogs injured since the state began keeping such reports in 2002.
Remember that this is based on reports filed by the racetracks themselves (the reports are, according to the release, "available upon request"). There may well have been additional injuries that were not serious enough to be reported to the state.