My 1 year old corgi has been doing this for the past few weeks. I have startedt to track what goes on at night to see if there is a pattern. Doesn't seem to bother him, but at the same time, I wouldn't think it is a good think either. Will take to the vet if it continues.
Well...from an amateur point of view (take it for what you pay for it!), I've had several dogs do that. I found it was because they were hungry. In fact, I came to call it "hunger-barfing." If the humans neglected to put the food down on schedule, the dogs would woof. As it were.
Try Sarah's strategy: give a late-night snack. And feed him the VERY first thing in the morning. Also, with my pooches it seemed that letting them chew on a rawhide anything -- fake bone, ears, whatever -- when they hadn't had anything to eat within the past few hours could also stimulate regurgitation of yellow bile. Feed smaller portions more often -- at least twice a day.
Tucker will do this from time to time. He's got a sensitive tummy. The vet's suggestion was to give him a small over the counter acid reducer like Prevacid or Prilosec. I get the generic at Costco and give it to Tucker first thing in the morning after he's had something different for dinner or after a Greenie.
Sophie used to do this. We just divided her total food amount for the day into three portions instead of the two we had been giving her, with the last feeding right at bedtime, and it stopped immediately. We had been doing the two feedings due to her seizure activity to try to equalize her blood sugar levels around the clock. The three times a day feedings seemed to help with that, too. Good luck.
Dogs have very acidic stomachs and so if their stomach gets empty it can get irritated and presto! Vomiting foam. I agree with the others: give a snack at bedtime and feed first thing in the morning.
If we give Jack a big high-protein biscuit right before his after-work pre-dinner walk, he never vomits. If we don't and we walk him on an empty stomach, he'll probably vomit 5 days out of 7.