PARALYSIS OF THE MUSCLES OF MASTICATION. 349 



(5.) PARALYSIS OF THE MUSCLES OF MASTICATION. 



PARALYSIS OF THE LOWER JAW (SO-CALLED). 



A condition in animals has been described where, in consequence 

 of diplegia of the masticatory muscles, the mouth cannot be closed. 

 It may more correctly be termed paralysis of the muscles of masti- 

 cation, or masticatory facial paralysis, as it is styled in man. 

 According to present information, it seems almost entirely confined 

 to dogs and cats, but Roll, Walthrup, and Lydtin have also seen it 

 in the horse. 



Both the masseter and the temporal muscles are supplied with 

 motor nerves from the inferior maxillary division of the fifth cranial 

 nerve. One-sided paralysis of this nerve is much less frequent in 

 animals than double-sided paralysis, but double-sided paralysis in 

 cats and dogs has been repeatedly described. The condition occurs 

 almost invariably during the progress of rabies, in fact is seldom 

 seen unassociated with it, and therefore its presence always awakens 

 suspicion. Although Gerlach insisted on its acceptance as a sure 

 sign of madness, dogs and cats thus affected often recover completely, 

 the surest proof that Gerlach's statement is incorrect. Korber and 

 Frohner have noticed the same thing in dogs. 



The anatomical changes causing the disease are at present 

 unknown ; they are probably due to some diseased condition in the 

 pons varolii. As a great number of nerve centres exist in this portion 

 of the brain, it is not remarkable that this disease is frequently 

 accompanied by other nervous disorders. In the case described by 

 Korber, paralysis of the pharynx and muscles of the throat and 

 breast supervened. Tempel records a case where a fibro-sarcoma 

 extending from the guttural pouch had pressed on the facial and 

 trigeminal nerves, paralysing them and producing the above symptoms. 

 But that isolated cases of paralysis of these motor nerves, occur, 

 and may recover, is shown by the following illustrations : — 



A grey pointer was sent to hospital, with the report that it had received 

 an excessive quantity of beer some days previously, and had afterwards 

 slept for a long time. When it awoke next day, its mistress remarked 

 that its tongue was hanging out, and that it was unable to close its mouth. 

 The animal appeared low-spirited ; the under jaw hung flaccid ; and 

 when pressed into position again fell. The tongue was dry and protruding ; 

 food could not be taken, though pieces of meat placed in the mouth were 

 swallowed with great relish. During the next few days the dog appeared 

 quiet, somewhat apathetic, and lay continuously in a corner of his kennel. 

 Five days later, the disease had already so far yielded to expectant treat- 

 ment that the animal could again take nourishment regularly. 



