A place like the Right Livers' Rest was bound to draw freaks, same as molasses draws flies. 1935, George Goodchild, chapter 5, in Death on the Centre Court: By one o'clock the place was choc-a-bloc.
Swallowing certain types of poisons may cause excessive salivation. According to the National Library of Medicine, pesticides can cause excessive saliva when they are swallowed. Venom from snake bites or insect stings is another type of poisoning that can cause the malady.
There are many different causes for excessive salivation. You will need to give a thorough history of your dog's health, including vaccination status, current medications, possible toxin exposure, a background history of symptoms, and any other possible incidents that might have precipitated this condition.