DEFINITION/OVERVIEW

• Sudden bilateral paralysis of trigeminal mandibular branches resulting in inability to close the mouth
  
• Lesions are characterized by extensive nonsuppurative trigeminal neuritis, demyelination, and rare axonal degeneration affecting all portions of the trigeminal nerve and ganglion without brain stem involvement
  
• Also referred to as dropped jaw, trigeminal neuropathy, mandibular paralysis

ETIOLOGY/PATHOPHYSIOLOGY

• Unknown
  
• Autoimmune disorder suspected

SIGNALMENT/HISTORY

• Primarily adult dogs
  
• Rare in cats

CLINICAL FEATURES

• Acute onset of a dropped jaw
  
• Inability to close the mouth
  
• Drooling
  
• Difficulty in prehending food, messy eating
  
• Swallowing is intact when food and water are placed in the caudal portion of the mouth
  
• Approximately one-third of affected dogs will exhibit loss of facial sensation
  
• Few dogs have sympathetic paralysis of the head (Horner’s syndrome)
  
• Long-term muscle atrophy depending on degree of axonal involvement

DIFFERENTIAL DIAGNOSIS

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