You might have never given your dog's salivary glands much thought, but these structures have likely proven to you many times that they're working, and quite efficiently too! Whether your dog drools because he's hungry or because he's getting a bit queasy during a car ride, that's proof that his salivary glands are doing their job. As with many other structures of a dog's body, the salivary glands carry out several functions and can also be prone to several problems. So today, let's discover more about a dog's salivary glands, the roles they play and conditions that affect them.
Introducing Your Dog's Salivary Glands
Hello, it's your dog's salivary glands talking! We're talking plural here because there are several of us populating your dog's body, more specifically, we're mostly located by your dog's upper and lower jaw.
Our major glands are found in matching pairs, meaning that there are two of us of each side of your dog's face and we consist of the following:
2 zygomatic glands, by the cheek bone near the dog's eyes
2 parotid glands where the head meets the neck
2 sublingual glands right under the dog's tongue
2 mandibular glands, by the dog's lower jaw.
There are also several minor glands distributed throughout your dog's lips, cheeks, tongue, hard palate, soft palate, pharynx and esophagus.
We are exocrine glands meaning that we release fluids through special ducts. The special fluid we release, as our name implies, is saliva which is delivered from each of our ducts straight to your dog's mouth.
Did you know? As Russian physiologist Ivan Pavlov demonstrated, higher centers of the dog's brain are capable of eliciting the parasympathetic response of drooling in anticipation of food.
We Help With Moisture
We help keep your dog's mouth nice and moist. A dry mouth can mean trouble when it comes to the proliferation of harmful bacteria. A moist mouth instead is the perfect recipe for a healthy mouth. Indeed, the saliva we produce is quite rich in antibacterial substances that helps keep the number of bacteria down.
You might not be aware of this, but here's a little hint: the level of moisture of your dog's mouth can help you assess your dog's level of hydration. A healthy dog who is well-hydrated will have gums that feel nicely moist, while a dog who is dehydrated will have gums that feel sticky, tacky and dry.
The saliva we produce also helps lubricate the passage of chewed-up food from the mouth through the esophagus and then all the way down to the dog's stomach. The blob of chewed up food is known as "bolus" and the more slippery it is, the easier it will slide down without causing damage.
Did you know? A 20 kilogram dog (around 44 pounds) is capable of producing anywhere between a half a liter up to 1 liter of saliva a day! The amount is usually higher in dogs who are fed dry foods.
We Aid Digestion
Have you ever heard the saying "the digestive process starts in the mouth?" This applies to dogs too. Indeed, we start the digestion process by breaking down some components found in your dog's food. As dogs chew, saliva indeed helps break down starch into individual sugar molecules, explains veterinarian Race Foster.
Not all of us though produce the same type of saliva. According to Dukes' Physiology of Domestic Animals, secretions from us may vary from watery to a thicker, mucoid-like consistency.
The parotid glands, for instance, produce a watery saliva rich in amylase, which is what helps dog digest starch.
The sublingual glands, on the other hand, produce a mucus-type of saliva rich in mucin, which helps the bolus travel from the mouth to the stomach.
Did you know? Your dog's salivary glands also increase salivation when there are irritating substances in the mouth and when your dog is anxious.
We Provide Evaporative Cooling
Dogs do not cool down primarily through their skin like humans do, but their main way of cooling off is by panting. You might not know this, but we can play a role in helping dogs cool down too. The saliva we produce indeed, can help Rover cool down when those temperatures soar in the dog days of summer.
You see, when your dog has his mouth open and breaths quickly after romping in the yard on a warm summer day, the moist surfaces of his mouth and tongue help cool him down by increasing evaporation.
If you take a close look at a dog panting after a long run, you will get a better picture how the saliva we produce help him cool down.
When Things Go Wrong
As with other structures of your dog's body, we are prone to problems, which sometimes can be even quite urgent. We can become inflamed, we can be subject to injuries and we can also be affected by cancer sometimes, although not commonly. Here is a brief rundown of several salivary gland problems in dogs.
Salivary Mucocele in Dogs
If our duct happens to get damaged and rupture, we may develop what's known as a salivary mucocele. When this happens, the saliva must drain somewhere and this often leads to soft (and often quite large!) swellings seen by the dog's neck and face. We may also cause presence of blood in the dog's saliva, trouble swallowing and sometimes eye pain or trouble breathing.
Mucocele in dogs can be caused by infections, tumors or a foreign bodies stuck in the duct (sialolithiasis). Depending on which one of us are affected, the mucocele may be given different names.
A Zygomatic mucocele affects the zygomatic salivary glands and saliva in this case tends to collects around the eye area. If the area swells too much, it can trigger exophthalmos, a protrusion of the dog's eyeball. Surgical removal of these glands may be more complicated due to the presence of ocular glands nearby and is best done by a specialist.
A Cervical mucocele tends to form a swelling by the upper area of the dog's neck and/or under the jaw. These should not be confused with reactive lymph glands or lymphoma, cancer of the dog's lymph glands.
A Pharyngeal mucocele may form by the dog's pharynx causing swelling that may impair a dog's ability to breath and can therefore require urgent veterinary care.
A Sublingual mucocele forms under the dog's tongue, When a dog's lingual glands are injured, a swelling in the floor of the dog's mouth, right under the tongue, forms. A mucocele under the dog's tongue is commonlhy called a ranula.
Mucocele are often treated by draining and removing the affected glands. Drainage alone is not resolutive considering that mucocele tend to re-occur several weeks or months later. How much does surgery to remove us cost? Cost tends to vary from one place and another and is also based on the location of the swollen gland and how enlarged it is. Prices for salivary gland removal in dogs may therefore range between 500 and 1,500 dollars.
Did you know? The copious salivation seen in rabid animals is not due to the overproduction of saliva, but the paralysis of the dog's pharynx, causing excess saliva to build up. Source: Colorado State University.
On top of mucocele and ranula, we may be affected from several other conditions such as salivary gland fistula, sialadenitis, (the inflammation of the salivary gland with the zygomatic gland most commonly affected) and sialadenosis, (a non-inflammatory swelling of the salivary glands.)
While cancer of the salivary glands is not very common, when it occurs, the dog's submandibular and parotid glands tend to be the most likely affected.
The Bottom Line
Figuring out whether we are swollen because of a mucocele, fistula, tumor or other cause, is not always straightforward. Bloodwork doesn't typically show any high white blood cell unless there is a major infection going on.
Diagnosis is most often obtained through the dog's medical history and results from aspirating the fluid within us though a fine needle aspirate. For instance, mucocele aspirates are often typically characterized by thick, ropy fluid that may have blood or a yellowish tint. A correct diagnosis is crucial because right where we are located, are also found a dog's submandibular lymph nodes which may swell when a dog has lymphoma, explains veterinarian Dr. Andy. So make sure you see your vet if you notice any problems with us. Your dog and us will thank you!
Your Dog's Salivary Glands
Disclaimer: this article is not meant to be used as a substitute for professional veterinary advice. If your dog is sick, has a lump or bump, or is acting abnormally, please see your vet at once.
- Colorado State University, Salivary Glands and Saliva, retrieved from the web on October 17th, 2016
- The Merck Veterinary Manual, Salivary Disorders in Small Animals, retrieved from the web on October 17th, 2016
- Dukes' Physiology of Domestic Animals, edited by William O. Reece, Comstock Publishing Associates; 12 edition (July 29, 2004)
- Best Pet Home Remedies, Salivary Infections in dogs, retrieved from the web on October 17th, 2016