Salivary glands in dogs are small organs positioned around the mouth and throat, responsible for producing saliva. These glands play a role in a dog’s overall health and comfort. Their secretions contribute to several bodily processes, from digestion to oral health.
Key Salivary Glands and Their Location
Dogs possess four primary pairs of salivary glands. The parotid glands are positioned just below the base of the ear, overlying the masseter muscle. These glands are flat and triangular, with their ducts extending forward to open inside the cheek near the upper molars.
The mandibular glands, larger and more rounded than the parotid glands, are located beneath the parotid glands, nestled between the angle of the jaw and the neck. They are often palpable as firm structures. Their ducts travel forward to open under the tongue, near the frenulum.
Adjacent to the mandibular glands are the sublingual glands, which consist of two parts: the monostomatic and polystomatic portions. The monostomatic part runs alongside the mandibular gland’s duct and shares a common opening under the tongue. The polystomatic part is a collection of smaller glands scattered along the floor of the mouth, each with its own duct opening directly into the oral cavity.
The zygomatic glands are situated beneath the eye within the orbit. These glands are smaller and flatter than the mandibular glands. Their ducts open near the last upper molar.
The Vital Functions of Canine Saliva
Saliva performs multiple functions. Primary among these is lubrication, which moistens dry food and forms a soft bolus for easy swallowing. This lubrication also helps protect oral mucous membranes from friction and injury during chewing.
Saliva also initiates chemical digestion. Canine saliva contains some lingual lipase, an enzyme that begins the breakdown of fats. This enzymatic action prepares food for further digestion.
Oral hygiene is another function, as saliva flushes food debris and bacteria from the teeth and gums. Saliva contains antimicrobial compounds like lysozyme, lactoferrin, and immunoglobulins (IgA), which help control bacterial populations and reduce the risk of infections. This cleansing action contributes to maintaining a healthy oral environment.
Saliva plays a role in temperature regulation. Dogs primarily cool themselves through panting, and evaporation of saliva from the tongue and oral cavity helps dissipate heat from the body, preventing overheating. Saliva also aids in taste perception by dissolving food particles, allowing them to interact with taste receptors on the tongue.
Common Conditions Affecting Canine Salivary Glands
Several conditions can affect a dog’s salivary glands. A common problem is a sialocele (salivary mucocele), a collection of saliva leaked from a damaged salivary duct or gland into the surrounding tissues. This presents as a soft, fluid-filled swelling, often seen under the jaw or in the neck region.
Sialadenitis refers to inflammation of one or more salivary glands, which can be caused by infection, trauma, or immune-mediated processes. Dogs with sialadenitis may exhibit pain when opening their mouth, reluctance to eat, and swelling around the affected gland.
Salivary gland tumors can be either benign (non-cancerous) or malignant (cancerous). These tumors present as firm, non-painful masses that grow slowly in the region of a salivary gland. Malignant tumors, such as adenocarcinomas, can be aggressive and may spread to other parts of the body.
Another condition is salivary gland necrosis, which involves the death of salivary gland tissue. This can result from various factors, including immune-mediated diseases. Dogs affected by necrosis may show signs such as excessive drooling, difficulty swallowing, or a painful swelling in the gland area.