My 10 1/2 year old purebread Australian Shepherd is having problems as he's aging. He is panting heavily at all times, like he's horribly hot and can't stand it. He has horrible hot spots that have developed over the last 1 1/2 years and that's getting worse, even with spray to help the spots. He seems to cough quite often, perhaps 2 or 3 times a day, but nothing is thrown up, just a quick cough that seems to clear him up. He has arthritis from being hit by a car as a puppy (we got him from Rescue after that) and so he has a limp, but sometimes now it's quite painful for him to move much. He still does the Aussie jump when he's excited though! I'm mostly worried about the panting/heavy breathing thing as someone told me it could be heart disease, do you you think? I'm taking him to the vet for his appointment next week.