I am sorry to hear you are worried about your dog's calcium level. I am a veterinarian and will do my best to help.
It would help to see all of the blood tests and to know if your dog has any symptoms, such as weight loss, increased thirst, coughing, etc. A single high calcium could be lab error, or could indicate a problem with his kidneys, parathyroid function, and worst case,high blood calcium can sometimes be a marker for cancer.
Sometimes I get a high calcium in a normal dog. Then I just wait, and recheck the calcium level in a couple of weeks. If it is back down to normal, I stop worrying about it.
I always check the anal glands in a dog with a high calcium. It is so easy to do, and high calcium can be a marker for a tumor of an anal gland.
Let me know if he has any symptoms and what other questions you have. Rebecca