S
Salivary Gland Disorders
BASIC INFORMATION 
DEFINITION
• Sialocele: accumulation of saliva that has leaked from a salivary gland or its duct into subcutaneous or submucosal tissue and consequent tissue reaction to saliva
• Necrotizing sialometaplasia: squamous metaplasia of the salivary gland ducts and lobules, with ischemie necrosis of the salivary gland lobules
CLINICAL PRESENTATION
HISTORY, CHIEF COMPLAINT
• Sialocele:
○ Acute, painful intermandibular swelling: initial stage of cervical salivary mucocele resulting from an inflammatory response; uncommon presentation
○ Swelling in the cranioventral neck region: cervical salivary mucocele at later stages when inflammation has subsided (more common presentation); typically found incidentally by owner; slowly enlarging or intermittently large, fluid-filled, and usually nonpainful.
○ Ptyalism, blood-tinged saliva secondary to masticatory trauma, poor prehension of food, and reluctance to eat: sublingual salivary mucocele
• Sialadenitis:
○ Painful swelling (dependent on location) along the vertical ear canal, caudal to the mandible, or orbital/retrobulbar area, with exophthalmos
• Salivary neoplasia:
○ Sometimes painful swelling (dependent on location) around the vertical ear canal or caudal to the mandible
(Copyright 2010 Alexander M. Reiter.)
PHYSICAL EXAM FINDINGS: All: see also History/Chief Complaint, above.
• Sialocele:
○ Fluid-filled, generally painless swelling in the cervical, sublingual, pharyngeal, or periorbital region
ETIOLOGY AND PATHOPHYSIOLOGY
• Sialocele:
○ Contrary to a true cyst which is lined by epithelium, a sialocele represents a tissue reaction to extravasation of saliva from a gland/duct complex and has a nonepithelial, nonsecretory lining consisting primarily of fibroblasts and capillaries.
○ Damage to salivary gland or duct associated with orofacial trauma may cause leakage of saliva into adjacent tissues. Generally this leakage is self-limiting and does not lead to mucocele.
• Sialadenosis:
○ Sialadenosis: salivary gland enlargement without cytologic or histologic abnormalities. Excessive saliva production may be associated with increased parasympathetic activity or changes in sympathetic innervation.
• Necrotizing sialometaplasia:
○ Squamous metaplasia of salivary gland ducts and lobules, with ischemic necrosis of the salivary gland lobules
DIAGNOSIS 
INITIAL DATABASE
• Sialocele:
○ Fine-needle aspiration and cytologic evaluation: clear or nontransparent, stringy, sometimes blood-tinged, often brownish fluid with a very low cellular content
TREATMENT 
ACUTE GENERAL TREATMENT
• Sialocele:
○ Needle drainage of mucocele; not recommended as repeat treatment option owing to rapid recurrence and risk of iatrogenic infection
○ Complete removal of involved salivary gland/duct complex with ligation of remaining duct and drainage of sialocele and surgical site
• Sialadenitis, sialadenosis and necrotizing sialometaplasia:
CHRONIC TREATMENT
• Sialadenitis, sialadenosis, and necrotizing sialometaplasia:
○ Pain management, antibiotics (based on culture and sensitivity of the fluid/tissue aspirate), nonsteroidal antiinflammatory drugs, antiinflammatory doses of glucocorticosteroids, and control of internal parasites have resulted in favorable responses in some cases.
POSSIBLE COMPLICATIONS
• Injury to the lingual nerve during removal of mandibular/sublingual gland/duct complex (lingual nerve is located dorsal and rostral to the gland/duct complex)
• Seroma/hematoma formation due to failure of having appropriately drained the sialocele and surgical site
PROGNOSIS AND OUTCOME 
• Sialocele: excellent with complete removal of the gland/duct complex, with appropriate drainage of the sialocele and surgical site
• Sialadenitis: excellent/good, depending on identification of initiating cause and response to treatment
• Necrotizing sialometaplasia: good/guarded, depending on response to medical treatment (such as phenobarbital)
PEARLS & CONSIDERATIONS 
COMMENTS
• Sialocele:
○ Placement of the patient in exact dorsal recumbency can lateralize cervical sialoceles that otherwise seem to be on the ventral midline, which is essential for knowing which side to approach surgically.
○ Sialoliths are concretions of calcium phosphate or calcium carbonate and may occur with chronic sialocele.
○ The intimate anatomic association of the sublingual and mandibular salivary glands and their ducts requires removal of both structures when a sialocele affects one of them.
• Sialadenitis, sialadenosis, and necrotizing sialometaplasia:
○ Be careful to differentiate these conditions from salivary neoplasia, as they can have similar clinical signs.
○ Complete surgical excision of affected salivary gland/duct complexes is virtually impossible, often unhelpful, and usually not necessary.
○ Be mindful of the many neurovascular structures in anatomic areas where drainage of salivary glands is required.
• Salivary neoplasia:
○ Be careful to differentiate this from sialadenitis, sialadenosis, and necrotizing sialometaplasia, as they can produce similar clinical signs.
○ Complete excision of a salivary neoplasm is unlikely and may increase morbidity; generally lesions are large and invasive at the time of diagnosis.
○ Be mindful of the many neurovascular structures in anatomic areas where salivary gland neoplasms are likely to occur.
○ Salivary neoplasia should be staged according to the TNM system (see p. 692) to permit appropriate prognostication and treatment plan.
Boydell P, et al. Sialadenosis in dogs. J Am Vet Med Assoc. 2000;216:872.
Hammer A, et al. Salivary gland neoplasia in the dog and cat: survival times and prognostic factors. J Am Anim Hosp Assoc. 2001;37:478.
Schroeder H, Berry WL. Salivary gland necrosis in dogs: a retrospective study of 19 cases. J Small Anim Pract. 1998;39:121.
Smith MM. Oral and salivary gland disorders. In: Ettinger SJ, Feldman EC, editors. Textbook of veterinary internal medicine. ed 6. Philadelphia: WB Saunders; 2005:1290-1297.
Spangler WL, Culbertson MR. Salivary gland disease in dogs and cats: 245 cases (1985-1988). J Am Vet Med Assoc. 1991;198:465.
Salmon Poisoning
BASIC INFORMATION 
EPIDEMIOLOGY
SPECIES, AGE, SEX: Dogs: any age, both sexes affected
RISK FACTORS: Exposure to a fresh brackish stream or beach is commonly elicited in the history.
GEOGRAPHY AND SEASONALITY: Infections are limited to the habitat range of the intermediate snail host (Oxytrema silicula) in western British Columbia, Washington, Oregon, northern California, and more sporadically in areas where fish carrying the causative organism, N. helminthoeca, migrate or are transported. Dogs have the greatest access to dead fish during spawning seasons (late summer to early winter).
ETIOLOGY AND PATHOPHYSIOLOGY
• Dogs acquire the causative organism (N. helminthoeca), and therefore the disease, from a fluke parasite (Nanophyetus salmincola) carried in the kidneys of salmon, and rarely other fish or salamanders.
• Rickettsial infection transmitted when flukes mature in the canine gastrointestinal (GI) tract:
○ Fluke maturation in the GI tract involves release of the rickettsiae, which are taken up into macrophages and disseminate to lymph nodes (especially mesenteric).
DIAGNOSIS 
INITIAL DATABASE
• CBC and serum biochemical findings are inconsistent but may include thrombocytopenia, lymphopenia, eosinophilia, hypoalbuminemia, and elevated alkaline phosphatase.
TREATMENT 
ACUTE GENERAL TREATMENT
• Hospitalization is recommended for intravenous fluid support and alleviation of vomiting and diarrhea.
• Mild cases: rickettsial infection can be treated with oral doxycycline (10 mg/kg q 12 h) or tetracycline (22 mg/kg q 8 h) for 7-14 days.
• Severe cases, particularly with vomiting/diarrhea: parenteral doxycycline (5-10 mg/kg IV q 12 h until oral form is tolerated) or ampicillin (20-30 mg/kg IV q 6 h). Oxytetracycline (7 mg/kg IV q 8 h × 3 days) has also been effective.
PROGNOSIS AND OUTCOME 
• Prognosis is fair to good in aggressively managed cases; improvement is usually noted within 2-3 days after treatment initiation but may take up to a week.
PEARLS & CONSIDERATIONS 
COMMENTS
• Salmon poisoning is an important cause of fever, lymphadenopathy, and severe GI signs in dogs in the Pacific northwestern United States and Pacific coastal Canada.
• Clinical signs are similar to hemorrhagic gastroenteritis, but affected dogs are typically febrile.
