Salivary Gland Disorders in Dogs

Does your dog drool excessively? There are many causes of hypersalivation, ranging from anxiety, motion sickness and local infection to serious conditions like rabies, distemper and chemical or plant poisoning. Drooling is an important symptom in dogs that should never be ignored. A number of years ago two of my dogs chewed on what turned out to be a Plague-infested dead rodent and a few days later started to drool continuously. If I had not taken them to the veterinarian for evaluation and treatment, they would have died, and they also could have passed Plague on to my husband and me through the infected fleas they picked up.

There are also certain breeds of dog that, because of the shape of their lips, seem to have drool hanging from their mouths all the time: Saint Bernards, Great Pyrenees, Newfoundlands, and some Hounds. This is normal for these dogs.

But what is abnormal, and when should you consider that your dog might have a salivary gland infection? As explained by veterinarian Dr. Delbert G. Carlson in his indispensable "Dog Owner's Home Veterinary Handbook", dogs have four principal pairs of salivary glands that drain an alkaline fluid into the mouth that aids digestion. The important thing to note about salivary gland infections that are not caused by underlying disease or toxic chemical exposure is that they are relatively rare in dogs. Usually they are associated with a general mouth infection or a salivary gland duct obstruction. Mouth infections that can lead to salivary gland infections include stomatitis (mouth mucous membrane inflammation), glossitis (tongue inflammation), gingivitis (gum inflammation) and periodontitis (inflammation of tissues supporting the teeth).

A mucocele is a cyst caused by a salivary duct becoming blocked by secretions, foreign bodies such as stones and plant awns, or particles of food. Any of these irritants can cause the duct to fill with fluid and eventually rupture, leading to formation of the mucocele. A specific kind of salivary gland mucocele is called a ranula or honey cyst. A ranula usually forms in the submandibular salivary gland and presents as a large, rounded swelling on the floor of the mouth and one side of the tongue. Mucoceles can become so large that they obstruct normal functions such as eating, swallowing and breathing. The fluid from a mucocele can be aspirated with a needle but often surgery is needed to remove it completely.

Salivary gland infections are at the very least uncomfortable for dogs and may lead to life-threatening problems if left untreated. If you suspect that your dog may have a salivary gland infection, have your vet evaluate him to rule out the possible causes of his symptoms.