Rep. Jerry Mitchell, the measure's Republican sponsor, says it would help prevent drug dealers from using dogs as weapons. The bill passed 95-19, the Chicago Tribune reported.
The neutering would have to be done within a week of a dog owner's arrest on a felony drug charge. Owners who fail to have the operation done would face an additional misdemeanor.
The law would apply only to dogs that have already been judged vicious under Illinois' Animal Control Act.