Dog Drooling: The Juicy Truth About Why Dogs Slobber

Holy ropes of drool, Batman! Your newly adopted St. Bernard puppy shakes his head, and the walls are covered in slobber. Is this normal? Will it get better or worse as he ages? Why is he drooling anyway? Come to think of it, what is drool?


What is drool and why do dogs do it?

Drool is saliva. It is produced in glands of which there are 3 sets—parotid, mandibular, and sublingual. Each produces a slightly different type of saliva with an individual purpose. This secretion can differ depending on the type of meal a dog eats. If the meal is dry food, the secretion tends to be more watery to soften the food, whereas if it is canned, softening is not needed. The secretion is often thicker in this case.

Saliva is constantly being made and swallowed. It keeps the mouth moist and free of food, as well as carrying away “bad” bacteria from the teeth. It contains tons of interesting enzymes, as well as electrolytes like sodium and bicarbonate. Saliva has multiple functions within the mouth including protecting the oral mucosa and the teeth, packing the food into a soft ball for easy swallowing, starting the starch digestive process, and destroying bacteria. Drooling can also serve to a cool a dog, since they have very few sweat glands. It’s a truly amazing fluid.

st bernard drooling out car window

E+ / jtyler

Is drooling ever normal?

It is not abnormal for your dog to drool sometimes. Pavlov showed in his famous bell experiments that anticipating a meal can make a dog salivate. Fear can also cause dogs to drool, as you will see in a storm-phobic dog. Drooling is a form of heat control for dogs called evaporative cooling. So, the answer is yes! Drooling can be normal and in response to the dog’s emotions or environment.

But there are times when drool is not normal. When excessive salivation occurs, the condition is called ptyalism. For instance, a dog with an infected tooth or gums can drool as a sign of dental disease. Nausea can cause drooling, as well. You may notice this particularly in dogs that become carsick. Tumors in the mouth—both benign and malignant, lodged foreign objects (such as a stick across the palate), trauma to the tongue or gums (notably electrical cord burns and caustic substance exposure), warts, and even metabolic diseases such as a liver shunt can cause drooling.

Certain drugs when administered orally have a noxious taste. Tramadol tablets, a pain medication, are known for this. More surprisingly, sometimes eye drops can be the culprit. Atropine is a common ophthalmic medication used to dilate the eye. It is extremely bitter and can cause frothing at the mouth.

irish setter drooling

Getty Images Plus / Wavetop

There are even infectious diseases that can cause drooling. The most notable of these is rabies. This is very rare to see in a dog with proper vaccinations, but it is possible. Distemper is another uncommon infection that may present with excessive salivation. Again, vaccinations generally protect against this viral infection.

Large and giant breed dogs like Mastiffs, St Bernards, and Great Danes usually drool frequently. In these breeds, it is “normal” in that the extravagant dripping saliva arises from the conformation of their lips, which are thick and droopy with many folds. Saliva tends to pool and drip, as a result.

When should I seek medical attention?

Unfortunately, if you’ve adopted a large or giant breed dog with floppy lips, slobber is going to be a regular part of the day. On the other hand, if your previously healthy dog with no history of significant salivation starts to drool, a visit to the veterinarian is definitely in order. The veterinarian will do a thorough physical exam to rule out illness. This should include a close examination of the oral cavity including gums, teeth, tongue, and the back of the throat (called the oropharynx). In some cases, depending on your dog’s temperament, this should be done under sedation. Even with an excellently behaved dog, it is difficult to fully examine the back of the mouth and throat, so sedation may be recommended. Even the best dog might not appreciate hands in his mouth.

Once the oral examination is complete, depending on what is found, the veterinarian may recommend more diagnostics such as xrays of the skull, infectious disease testing, or biopsy if a tumor is present. If a cause is readily apparent, a treatment plan will be proposed based on the this. Some examples of possible treatments include a dental for tooth decay and gingivitis or mass removal and biopsy if a tumor is found.

As with all questions of dog health, when in doubt, a phone call to your veterinarian is never a bad idea.


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