My name is***** and I am sorry to hear that Bobby is having drooling this evening.
Can you examine his mouth? Can you pry it open and look at the upper jaw as well as between the teeth?
Is there anything that he could have eaten such as trash, plants, bugs, etc that could be very irritating to the mouth or cause nausea?
Drooling in dogs is usually because of eating something that tastes really bad or nausea. Nausea can be from eating something irritating to the intestines or possibly pancreatitis, colitis, intestinal parasites, and others.
Lastly some toxins can cause drooling such as slug bait.
If the oral exam is normal, I would recommend giving a Pepcid 30mg (1.5 adult human tablets). If the drooling is from nausea, this will hopefully help.
If Bobby starts vomiting, you will need to consider taking him to the local animal emergency room this evening.
If he is still drooling or won't eating in the morning, you should take him to see your regular vet in the morning.
Best regards, ***** ***** this answer helps you.
Feel free to contact me if you have any more questions.
Kansas State University,
College of Veterinary Medicine Class of 2001