Dropped jaw—mandibular neurapraxia in the dog

Abstract

Five canine cases of inability to close the mouth are presented. In each instance the probable cause was bilateral, temporary paralysis of the mandibular branch of the trigeminal nerve. All the cases responded satisfactorily to having the mouth loosely muzzled for a period of up to 3 weeks.

Maxillofacial Injuries and Diseases That Cause an Open Mouth in Cats

“…[35][36][37] The mouth hangs down passively, can be closed by manually lifting the mandibles, and falls back into its former dropped position when released. To the authors' knowledge, trigeminal neuropathy in cats has not been previously reported, although the authors have seen one such case in a 6-year-old cat.…”

“…36,38 Trigeminal neuropathy appears to be more commonly idiopathic in dogs although it has also been reported secondary to malignancies and rabies. [35][36][37] The cat treated by the authors was fed through an esophagostomy tube and continued on pain medications without other treatment. [35][36][37] The cat treated by the authors was fed through an esophagostomy tube and continued on pain medications without other treatment.…”

“…35,39,40 Dogs with idiopathic trigeminal neuropathy typically return to normal motor function and restoration of mandibular movement after 2 to 3-weeks. [35][36][37] Central neurologic lesions and rabies should also be considered if there is evidence of other cranial nerve deficits or systemic weakness. The cat regained most voluntary jaw movement after 15 to 20-days and full control returned after 32-days.…”

“…observed by the authors include an acute onset of a dropped jaw, difficulty prehending, messy eating, and drooling. [35][36][37] The mouth hangs down passively, can be closed by manually lifting the mandibles, and falls back into its former dropped position when released. Unlike cases of bilateral caudal mandibular fractures, animals with trigeminal neuropathy are not painful when the mouth is manipulated.…”

“…[5][6][7]12,17 The mandibular nerve and its branches to the muscles of mastication are closely related to the joint capsule of the TMJ and stretching of the nerve during wide opening of the mouth has been postulated to be a cause of interference with nerve function. 15,36 Dissection of the nerve confirms that the mandibular nerve, temporalis, masseter and likely the medial and lateral pterygoid muscles are stretched when the mouth is opened maximally however the association has not been thoroughly investigated. 36,38 Trigeminal neuropathy appears to be more commonly idiopathic in dogs although it has also been reported secondary to malignancies and rabies.…”