I had one about 20 year ago, slipped it on a hare he ran it for about a minute before they went out of sight, Then I heard the noise in the distance n thought he'd got it, I ran over in the direction I'd heard it with a big daft smile on my face n by the time I got there I realised the noise was actually the dog coughing it's lungs up it sounded like a steam train never known anythin like it before or since lol..