ISSN 2398-2969      

Submandibular gland disease

Clapis

Introduction

  • Cause: causation in rabbits usually unknown. Varied in other species – depends on specific disease process.
  • Signs: early stages may be asymptomatic. Pain, swelling around the mandible, ptyalism, anorexia, ileus, masticatory difficulties and dental malocclusion.
  • Diagnosis: history and clinical examination, radiography, cytology, histopathology, bacteriology, virology, computed tomography.
  • Treatment: medical management of inflammation/infection. Surgical resection in some cases. Supportive care.
  • Prognosis: good to guarded depending on cause.
Print off the Owner Factsheet on Submandibular gland disease to give to your clients.

Normal anatomical features

  • Rabbits possess several major salivary glands which include paired parotid, submandibular and sublingual glands.
  • Rabbit submandibular gland contain many types of cell surface neurotransmitter receptors such as muscarinic receptors (m1 and m3).
  • Secretion varies between glands:
    • Most glands require a humoral (such as food intake) or nervous stimulus.
    • Submandibular glands secrete saliva components spontaneously and continuously but will increase secretion rate in response to stimuli.
  • Submandibular glands are a seromucous gland.
  • Salivary gland disease is very rare in rabbits.

Pathogenesis

Predisposing factors

General

  • Infectious or inflammatory processes of the oral cavity may extend to the salivary glands and ducts.

Specific

  • Necrotizing sialometaplasia has only been reported secondary to facial trauma in a rabbit.

Pathophysiology

  • Salivary gland abscessation: possible, but no reports in literature.
  • Necrotizing sialometaplasia is a rare inflammatory process affecting the submandibular salivary glands:
    • Cause not well understood but likely due to ischemic infarct of the gland.
    • Viral and autoimmune causation has been proposed in dogs.
    • Experimentally induced in rabbits following photodynamic therapy of the mandible.
    • Single report in a 7-month old male laboratory rabbit: facial trauma of unknown cause → comminuted fracture of the mandibular body, ramus and symphysis → secondary trauma to submandibular gland and vasculature → thrombosis of gland → salivary gland infarction → coagulative necrosis and swelling of affected gland.
    • Must be differentiated from neoplastic processes to prevent inappropriate treatment.
  • Adenocarcinoma:
    • Uncommon in domestic animals.
    • No reports of neoplasia specific to submandibular gland.
    • Adenocarcinoma of the parotid gland involving the submandibular gland has been reported:
      • Single report in 7-year old female pet rabbit.
      • Aggressive neoplastic mass of the parotid gland → expansile with compression and replacement of surrounding musculature and facial nerves → Infiltration and destruction of adjacent submandibular gland → invasion of mandibular ramus and tympanic bulla.
  • Sialocele:
    • No reports of disease specific to submandibular glands.
    • Single report of a sublingual gland ranula in a laboratory rabbit:
      • Cystic structure noted under the tongue at necropsy.
      • Gross morphology similar to oral papilloma.
      • Incidental finding.
    • Infectious, inflammation, trauma, sialoliths → obstruct salivary ducts → Failure to drain saliva from gland → duct dilation with pseudocyst → secondary dilation of internal gland ducts → gland swelling.
  • Sialadenitis:
    • Experimental induction in rabbits using autologous lymphocytes targeting lacrimal antigens.
    • Spontaneous infectious or autoimmune causes possible but no reports in literature.
  • Sialectasis:
    • Dilation of the salivary duct.
    • Single report in a 10-year old female pet rabbit.
    • Congenital abnormalities, sialolith formation and infectious processes → stricture of the salivary duct → failure to drain saliva from gland → duct dilation and swelling.
    • Cocci and Candida albicans have been implicated as possible etiological agents in this case.
  • Sialolithiasis: possible but no reports in literature.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Donnelly T M & Vella D V (2016) Anatomy physiology and non-dental disorders of the mouth of pet rabbits. Vet Clin North Am Exotic Pract 19 (3), 737-756 PubMed.
  • Gardhouse S, Sanchez-Migallon Guzman D, Petritz O A et al (2016) Diagnosis and treatment of sialectasis in a domestic rabbit (Oryctolagus cuniculus). J Exotic Pet Med 25 (1), 72-79 VetMedResource.
  • Bercier M, Sanchez-Migallon Guzman D, Stockman J et al (2013) Salivary gland adenocarcinoma in a domestic rabbit (Oryctolagus cuniculus). J Exotic Pet Med 22 (2), 218-224.
  • Villlano J & Cooper T K (2013) Case report: mandibular fracture and necrotizing sialometaplasia in a rabbit. Comp Med 63 (1), 67-70 PubMed.
  • Dorje F, Levey A I & Brann M R (1991) Immunological detection of muscarinic receptor subtype proteins in rabbit peripheral tissue. Mol Pharmacol 40 (4), 459-462 PubMed.
  • Weisbroth S H (1975) Sialocele (ranula) simulating oral papillomatosis in a domestic (Oryctolagus) rabbit. Lab Anim Sci 25 (3), 321-322 PubMed.

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