225 ILCS 115/18
Unless otherwise contractually provided between veterinarian and client, a veterinarian may dispose of any animal abandoned in his establishment, provided he shall give notice of his intention to do so to the owner at the last-known address by certified mail, return receipt requested, and shall allow a period of 7 days to elapse after the receipt is returned before disposing of such animal. But if the owner cannot be located at such address, the veterinarian shall give such notice by publication in a newspaper published and having a circulation in the area in which such owner was last known to reside and shall allow a period of 7 days to elapse after such publication before disposing of such animal.
A veterinarian who, on his own initiative or other than at the request of the owner, gives emergency treatment to a sick or injured animal shall not be liable for damages in the absence of gross negligence. If the veterinarian performs a euthanasic act on an animal, there is the presumption that such was a humane act necessary to relieve the animal of suffering.
225 ILCS 115/18