My dog Lubo recently had an op to remove a lump from his lower eyelid and two from his head.  We mentioned to the vet that he is liable to vomit after he drinks loads and loads when he comes in from walks, or after dinner and he thought he'd do a blood test just to be sure.  He had the tests and it came back (in simplistic laymens terms) that his blood has far too many red blood cells.  They did the test again and again its come back with an obviously high level of red cells. 

He's now being sent to the queen mother hospital for animals for further tests.  However, when I phoned the normal vets up about the appointment the receptionist said 'Oh, yes, this is about his heart isn't it'.  I don't know whats wrong with him, I know this is why they are doing more tests but I have got absolutely no idea.  Why do you get extra blood cells?

Hi can't say for sure in dogs but in humans a high red blood cell count means (In laymans terms) the blood is too thick and may lead to clots and strokes. Maybe this is why they mentioned the heart. I cannot see that it would be a problem to treat if thats the case as there are plenty of drugs around to thin the blood. No doubt the vets will soon have the full information for you and will be in a possition to treat it. Good luck
Aileen