IVRI Anatomy
A free veterinary anatomy learning platform for B.V.Sc., M.V.Sc., DVM and veterinary medicine students worldwide, developed at the Veterinary Anatomy Section, ICAR-Indian Veterinary Research Institute, Bareilly—covering VCI/MSVE and international university curricula through regional anatomy, histology, embryology, comparative biomechanics, clinical notes, quizzes and revision.
Three pairs of major salivary glands + many minor (buccal, lingual, palatine, pharyngeal) glands embedded in the oral mucosa.
1. PAROTID GLAND (Glandula parotis):
• Largest salivary gland in horse and ox.
• Located in the parotid region — caudal & ventral to the ear, behind the ramus of mandible.
• Type: Serous. Salivary alpha-amylase can be measured in horses, but saliva is not taught as a major site of equine starch digestion.
• Stenson's duct (Parotid duct, ductus parotideus):
– Crosses ventral border of mandible alongside facial artery & vein.
– Ascends on lateral surface of masseter.
– Pierces the buccinator to open on the parotid papilla; in cattle the opening is commonly described near the upper fifth cheek-tooth region, with species variation.
• Surgical importance: The facial course of the duct must be protected during surgery for parotid fistula and other procedures involving the cheek.
2. MANDIBULAR GLAND (Glandula mandibularis):
• Located ventral to parotid, in intermandibular space.
• Type: Seromucous (mixed).
• Wharton's duct (Mandibular duct):
– Runs on the floor of the mouth.
– Opens at the sublingual caruncle beside frenulum, just behind lower incisors.
• Common site for sialocele/ranula if duct ruptures.
3. SUBLINGUAL GLAND (Glandula sublingualis):
• Lies under the floor of mouth, below mucosa.
• Two parts:
– Monostomatic part — single duct (Bartholin's duct).
– Polystomatic part — multiple small ducts (Rivinian ducts) opening directly on the sublingual fold.
• Type: Mucous (thick, viscous secretion).
SALIVARY OUTPUT:
• Ox: ~100-150 L/day (mostly parotid, alkaline, buffers rumen).
• Horse: ~10-12 L/day.
• Dog: ~1 L/day.
• Saliva is principally water and contains species-dependent bicarbonate, mucins, antimicrobial factors, immunoglobulins and variable enzyme activity.
FUNCTIONS:
1. Lubrication of food → easier swallowing.
2. Lubrication and buffering; measurable salivary alpha-amylase in horse and dog should not be presented as a major established oral digestive pathway.
3. Buffering — bicarbonate stabilises rumen pH.
4. Antibacterial (lysozyme + IgA).
5. Cooling (panting in dog evaporates saliva).
6. Taste (dissolves food → reaches taste buds).
| OX | Parotid huge — ~400 g; major rumen buffer source. |
| HORSE | The parotid is the largest major salivary gland. Salivary flow rises markedly during mastication; 'only when chewing' is too absolute. |
| DOG | Mandibular and sublingual most prominent on examination. Sialocele common — Wharton or sublingual duct rupture. |
| CAT | Smaller glands; cat saliva contains Fel d 1 (allergen for humans). |
Explore the hidden mechanics of why structures are present, absent or modified across domestic and wildlife species—and how each anatomical design supports movement, function and clinical practice.
Explanation goes here.