Be sure to read your dogs shampoo label, and make sure that it is non- toxic. The label should clearly state that it is NON-Toxic. If it does not state Non-toxic, then you need to call your vet.
Also, There may be a phone number somewhere on the label, that you can call and ask them questions.
You need to make sure that your shampoo is not toxic to your dog.
If the shampoo proves to be nothing to worry about, then....
Another reason dogs drool, is when they have something stuck in their mouth, or throat.
Be sure to check out the safety of your dogs shampoo...
Connie
From the sound of it, the soapy bath water is almost certainly to blame. This will correct itself within a day, if that's what it is. Don't try forcing him to eat for the next 24hrs, as dogs know instinctively not to put food in their stomach when they are feeling nausious. If you do offer him food, make it something easy to digest like cooked chicken and white rice (beef is actually much more difficult to digest, so this could have stirred up the stomach upset again). I wouldn't worry too much at this stage, but if he continues to be lethargic and is still off his food in a couple of days, I would take him to the vet for a professional opinion. Tony