30 Dropped jaw INITIAL PRESENTATION Inability to prehend food or toys, slow, messy eating: drops food and dribbles water around the bowl, drooling, salivating (pseudoptyalism), jaw hanging open, unable to close mouth, tilting or throwing the head back to eat. INTRODUCTION Prehension is the grasping of food or objects with the mouth. The inability to prehend food has been called oral dysphagia. The most obvious deficit occurs with bilateral trigeminal nerve paralysis. The mandibular branch of the trigeminal nerve (CN V) innervates the muscles of mastication. Unilateral paralysis does not interfere with feeding. Bilateral paralysis causes the jaws to hang apart at rest. The animal attempts to eat but food falls from the mouth. Food placed at the back of the mouth can be swallowed. Tongue paralysis as a sole deficit is rare. Weak tongue retraction has been noted as an examination finding, not a presenting complaint, in myasthenia gravis. A pit bull pup with episodic paralysis (from suspected hyperkalaemic periodic paralysis) precipitated by exercise had flaccid neck, limb and tongue muscles. A fractured hyoid bone, strenuous tongue manipulation in small dogs and brainstem tumours are also reported causes. The rare conditions of muscular dystrophy, congenital myotonia, and acromegaly cause hypertrophy of the tongue and its protrusion from the mouth. The lips play a part in prehension although not as prominently as in primates or ungulates. Nevertheless, always consider facial paralysis as a cause of dropping food. The flaccid paralysis of upper lips leads to them being caught between teeth during prehension. This is painful, and the mouth is opened again. Food is also trapped between gums and lips despite a functional tongue and jaw. Oral or pharyngeal pain or obstruction are common causes of a failure to prehend food. Teeth chattering has been reported in cats with dental disease. SIGNALMENT A 5-year-old female Hungarian vizsla. CASE PRESENTING SIGNS Inability to close the mouth. CASE HISTORY The dog suddenly developed a dropped jaw 1 week prior to referral. The owners had noticed the water in the drinking bowl being frothy the day before the jaw was visibly hanging open. The next day the right third eyelid became prominent. Muscle loss on the head was noted bilaterally. The dog tried to pick things up but could not do so. No regurgitation, choking or vomiting were reported. Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: Metabolic encephalopathy: hepatic encephalopathy Meningioma Behaviour change – an introduction Idiopathic facial paralysis Stay updated, free articles. Join our Telegram channel Join Tags: Saunders Solutions in Veterinary Practice Small Animal Neurology Sep 3, 2016 | Posted by admin in SMALL ANIMAL | Comments Off on Dropped jaw Full access? Get Clinical Tree
30 Dropped jaw INITIAL PRESENTATION Inability to prehend food or toys, slow, messy eating: drops food and dribbles water around the bowl, drooling, salivating (pseudoptyalism), jaw hanging open, unable to close mouth, tilting or throwing the head back to eat. INTRODUCTION Prehension is the grasping of food or objects with the mouth. The inability to prehend food has been called oral dysphagia. The most obvious deficit occurs with bilateral trigeminal nerve paralysis. The mandibular branch of the trigeminal nerve (CN V) innervates the muscles of mastication. Unilateral paralysis does not interfere with feeding. Bilateral paralysis causes the jaws to hang apart at rest. The animal attempts to eat but food falls from the mouth. Food placed at the back of the mouth can be swallowed. Tongue paralysis as a sole deficit is rare. Weak tongue retraction has been noted as an examination finding, not a presenting complaint, in myasthenia gravis. A pit bull pup with episodic paralysis (from suspected hyperkalaemic periodic paralysis) precipitated by exercise had flaccid neck, limb and tongue muscles. A fractured hyoid bone, strenuous tongue manipulation in small dogs and brainstem tumours are also reported causes. The rare conditions of muscular dystrophy, congenital myotonia, and acromegaly cause hypertrophy of the tongue and its protrusion from the mouth. The lips play a part in prehension although not as prominently as in primates or ungulates. Nevertheless, always consider facial paralysis as a cause of dropping food. The flaccid paralysis of upper lips leads to them being caught between teeth during prehension. This is painful, and the mouth is opened again. Food is also trapped between gums and lips despite a functional tongue and jaw. Oral or pharyngeal pain or obstruction are common causes of a failure to prehend food. Teeth chattering has been reported in cats with dental disease. SIGNALMENT A 5-year-old female Hungarian vizsla. CASE PRESENTING SIGNS Inability to close the mouth. CASE HISTORY The dog suddenly developed a dropped jaw 1 week prior to referral. The owners had noticed the water in the drinking bowl being frothy the day before the jaw was visibly hanging open. The next day the right third eyelid became prominent. Muscle loss on the head was noted bilaterally. The dog tried to pick things up but could not do so. No regurgitation, choking or vomiting were reported. Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: Metabolic encephalopathy: hepatic encephalopathy Meningioma Behaviour change – an introduction Idiopathic facial paralysis Stay updated, free articles. Join our Telegram channel Join
