You Jasper look like he has some turkish angora in him as does my vixen. And my Vixen pants all the time too. My vet said Vixen was perfectly healthy. But excessive panting one of the signs of a heart defect. I was worried about that with Vixen excessively worried so I had her checked just in case and nothing. I am sure it is the same for Jasper. Have you had Jasper neutered yet? If yes and he has been under anistetic then I would say 9/10 he has no heart defect. I would take him in for a check on it anyway though. Just to easy you mind and to be sure.