Original sentence: , particularly in Massachusetts, Colorado, Iowa and Rhode Island.Accidents and disease are common also common killers among racing Greyhounds.In 2005, an endemic of respiratory failure killed dozens of dogs and left over 1200 quarantined in the U.In the late 20th century several Greyhound adoption groups were formed.Previously, over 20,000 retired Greyhounds a year were killed; recent estimates number in the thousands
Edited sentence: In part due to the feelings of some people that the conditions under which racing Greyhounds are kept are inhumane, in the late 20th century several Greyhound adoption groups were formed.Previously, most retired Greyhounds were killed; many still are