Pavlov could drool a dog by ringing a bell. The dog had learned that the bell meant that the food was being served. He already started his mouth watering.
Drooling can be a completely normal reaction.
If your dog is already slobbering the visit, this is a problem. Especially dogs with hanging lips sometimes do not keep dry. In those cases, be clear and strict to your dog. He does food at a fixed time, in a fixed place. There is no food for him outside, so there is no reason to drool.
Drooling can also indicate a disease :
Facial muscle paralysis (Facialis paralysis)
In dogs with this paralysis, the lips close insufficiently and (neat) eating and drinking is a problem.
This disease can have various causes, for example a middle ear inflammation. If the cause is removed, the dog can eat normally again, without excessive drooling.
Paralyzed mandible (mandibular paralysis)
Dogs with a paralyzed (drooping) lower jaw can not drink properly. They are lying around in the water tank all the time, but it seems to be fuller rather than less full. There is a layer of saliva in the water tank.
Animals with this condition should be helped with food and drinks (for example by putting a snout around so that the beak can open up to 1 cm).
Spontaneous recovery occurs in most cases.
Inflammation oral mucosa
An inflammation of the oral mucous membranes (stomatitis) causes the dog to produce a lot of saliva. Good examination of the mouth (under anesthesia) can find a possible cause.
If the dog especially stinks from his mouth, lip pleoidermatitis can also occur.
Swallowing problems and esophagus problems
If an animal eats something that lingers in the throat or esophagus, it leads to panic in the dog and usually a substantial saliva production.
This is an emergency.
Call your vet right away. Often a foreign object can be removed endoscopically.
Also paralysis of the throat (rare) or paralysis of the esophagus (megaoesophagus) can lead to excessive saliva loss and regurgitation of food and drink. (regurgitation is vomiting without abdominal press)
Nauseous animals can drool, smack, peas, eat grass, vomit, and have less appetite.
If the symptoms do not improve within a few days or if your dog has become ill, it is best to contact a veterinarian.