Golden Vomiting immediately after drinking water

Question
Has anyone had experience with a dog who vomits immediately (within 2 minutes) of drinking water.  My 6 year old Golden Retriever has started doing this for about the past 2 months.  He has always had a sensitive stomach and has acid reflux where he spits up a small amount (half dollar size) about once or twice a day.  He has been taking 2 75mg. Rantidine (acid reducer) tablets once a day for 3 or 4 years, now.  Since the recent episode, the vet has had me try him on 15 mg. Reglan twice a day (it didn't work), and now 1 gram Carafate every 8 hours.  This is his 5 day on Carafate and today was the first day he threw up the water, but I've been limiting his water intake until today.  If he drinks only a little water (say lapping for 15 seconds or less) he keeps the water down.  It is only when he drinks for a longer period, or more water, that he vomits.  The vet has never heard of water specific vomiting, and my dog is scheduled to be anesthetized and scoped on August 10.    Any information would be appreciated.  Thanks

Answer
This sounds very much like megaesophagus, and is a hereditary condition when seen in puppies. It can also develop in older dogs for no known reason. Here are a couple sites to help explain this disease for you:

http://www.upei.ca/cidd/Diseases/GI%20disorders/megaesophagus.htm  

http://www.brightleaf.com/rusty/megaesophagus.htm

There is also a support group for owners of dogs with this condition: http://pets.groups.yahoo.com/group/megaesophagus/

Karen