I am sorry to hear your dog ate this large bone. My name is Rebecca. I am a veterinarian and will do my best to help.
I am not worried about small pieces in his intestinal tract; those likely will pass. I am worried if he swallowed a large piece; that could cause a blockage. Dogs have been known to swallow pieces large enough to cause intestinal obstruction. How big a dog is he?
The other concern is pancreatitis, which would also cause vomiting. How old is he? We usually see pancreatitis in dogs older than 4.
How long ago did he get the ham hock?
You can give famotidine (Pepcid AC) for vomiting. I need his weight to give you the dose. However, if he has an intestinal blockage or pancreatitis, he will probably need medical attention.
If he were mine, I would not try to feed him, but would try to get him to drink. He needs to stay hydrated. If he won't drink, or if everything he drinks comes back up, then I would take an Xray to see how big the bone pieces are. If the bone pieces are not that big, I would next do a blood test for pancreatitis especially if he is over 4 years old.
Check his gums, are they pink? If he has a blockage or pancreatitis, his gums might look pale.
Let me know how he is doing and what other questions I can answer. Rebecca