Buddy was 14. We had him his whole life. Heartworm disease - we couldn't watch him suffer any more. One of the hardest things I've done in my life was holding him while the vet gave him the shot. My wife couldn't stay in the room. He was really her dog. If you have dogs, PLEASE get them on heartworm prevention medication. He was an old dog, and had some other health issues - he probably wouldn't have lived much longer anyway. But to know that this was preventable... I feel so terrible. I have been putting myself through hell all day.