The incidents occurred late last week while the dogs were housed in a kennel.
Sheriff Daniel McEathron said the dogs were acting strangely and were sent to the vet where it was determined they ingested anti-freeze. A retired K-9, Logan, and a dog owned by the kennel's owner had to be put down. Two other dogs were treated and are recovering.
McEathron, who at one time spent 20 years as a handler in the K-9 unit, said the dogs are like part of the department. He said it's tough because the dogs spend so much time with the deputies, they feel bad if anything happens to them.
Investigators believe this is an isolated incident and they are treating this as a criminal matter. Animal cruelty, especially to police dogs, is considered a felony.
Anyone with information is urged to call the Warren County Sheriff's Department.