My black lab who is about a year old just will not eat. He has never had any problems with not eating before. He just stopped eating about 4 days ago. I took him to the vet and he came back completely healthy and the vet force fed him a couple cans of dog food, but he still will not eat. He may also be consstupated because I have not found any stool. He has also been vomiting a foamy white substance.

For a healthy dog to suddenly quit eating unless there is some unusual stress, just does not happen. I am talking about being rehomed or the owner dying. If nothing extreme has happened in the dogs life, I would take it to another vet. The vomiting had started before the vet check? If not, You might give the first one a second chance.

Continue to offer it its regular food.