Dogs have a variety of salivary glands throughout their head and mouth that produce saliva to aid in digestion, temperature regulation and cleansing of the mouth. The most common glands include the zygomatic, located near the eye; the mandibular, near the jawbone; the sublingual, under the tongue; and the paratoid, near the ear canal. Various infections and conditions caused by bacteria, viruses or injury affect these glands.
Rabies is a severe viral infection spread to dogs through a bite from another infected animal. The rabies virus collects in an animal’s salivary glands, making transmission through saliva easier. One symptom of a rabies infection is excessive or frothy saliva. Rabies is a zoonotic disease, meaning it can pass between species and infect humans. Before diagnosing a salivary gland condition with excessive salivation, a veterinarian must rule out possible rabies exposure before performing an oral examination.
Mumps is another zoonotic condition that affects a dog’s salivary glands. When a dog is exposed to a person infected with the mumps, the paramyxovirus virus spreads into the dog’s paratoid salivary glands. The virus causes swelling in the glands, noticeable by swelling under the ears. Other symptoms include fever and a lack of appetite. In dogs, the mumps does not usually require treatment and will run its course in five to 10 days. If your dog becomes dehydrated, intravenous fluids may be necessary.
Salivary mucoceles is a condition that causes a mucus-filled saliva sack to develop in the soft tissue of the mouth due to an injury or infectious blockage to a salivary gland. The sublingual and mandibular glands are most often involved, though mucoceles can affect any gland. Symptoms depend on the gland involved, but can include facial or oral swelling, blood in the saliva, difficulty eating or swallowing, eye pressure, difficulty breathing and masses in the neck.
Other conditions, such as periodontal disease, abscessed teeth or other mouth infections affect the salivary glands and cause hypersalivation, or excessive drooling. Excessive saliva can prevent mouth infections from healing, resulting in salivary fistulas. Often, treatment of the underlying infection is enough to clear the gland infection, though in some cases, surgical removal of the gland is necessary.