Our Greyhound, Blue Bob came to us with gum disease which, unfortunately, means that every 6-8 months he has to go in to the vets for dental work. Whenever he does, we ask them to screen his blood to monitor his health. Every time, the bloods would come back with a significantly high creatinine level. At first, they were concerned about his kidney function but nothing would show up in his urinalysis to suggest there was a problem. Blue Bob is an extremely well muscled Greyhound so they put the high creatinine level down to this. However, a while ago, I was doing some research for a course I was studying and came across some articles about Greyhound idiosyncrasies. Greyhounds have some differences in their haematology that some vets aren't aware of. I was quite nervous of offending my vet by telling her this but when I did, she was very grateful and asked me to send her all the information I could. I'm glad I found this information as it spares Blue Bob the repeat blood tests he had to endure. Here is some of the information I have found.
If your vet is unaware of these differences, it may be useful to let them know for future reference. If nothing else, it could spare your Greyhound from having endless blood tests in an attempt to find out what is wrong.