Sliced ham is the meat that is part of the upper part of a pig’s leg which has been smoked or salted. It has been preserved by salting, smoking or wet curing and was traditionally from hind leg of swine.
Unfortunately they cant at all. Meat is not a good food for them to eat and is toxic in some cases and does not hold any nutritional value for them. The preservatives that ham will have been prepared with are also harmful to dragons.
So it is not a good food for them to eat.