DISEASES OF THE NERVOUS SYSTEM. 



EXAMINATION OF THE NERVOUS SYSTEM. 



Disturbances of the nervous system are marked by impairment of 

 consciousness, sensitiveness, and motility. Besides these, there are 

 complications in the functions of the eyes, ears, taste and smell, and also 

 the digestive system. 



1. The Disturbances of consciousness are variously defined according 

 to their intensity. Dulness (indifference to any external influences), 

 somnolence (drowsiness, sleepiness, when the patient is awakened easily), 

 stupor (deep sleep, with difficulty in arousing the patient), coma (entire 

 unconsciousness, where the animal is not disturbed by external influences) . 

 In extreme cases of unconsciousness, all sphincters of the body become 

 relaxed. Such cases are found in the various diseases of the brain and 

 its coverings and in cases of injury and concussions of the brain; it is also 

 seen in poisoning by narcotics, in uraemia, in acute anaemia, and in all 

 diseases accompanied by intense fever and pain. Short attacks of un- 

 consciousness may occur in the form of dizziness, and are seen occasion- 

 ally as the result of great excitement or pain (in operations) ; and also 

 idiotism, which occurs in rare instances as a result of distemper, when it 

 assumes the nervous form. 



2. . Disturbance of Sensitiveness. — This is not easily recognized in 

 the dog. In all instances it is advisable to cover the patient's eyes, and 

 compare the sensitiveness of the affected side with that of the healthy one. 

 In cases of haemaphraic diseases, we test the sensitiveness of the skin by 

 pricking it slightly with a needle or letting cold water drop upon it, so as to 

 produce some irritation or symptom of pain. A test may also be made 

 by means of a battery; still this method is not as reliable and practical as 

 the needle and cold-water test. 



Total anaesthesia occurs, as a rule, from poisoning, and must not be 

 mistaken for a want of reaction, when in a comatose condition. Local 

 anaesthesia — that is to say, a more or less circumscribed or disturl)ed 

 zone of sensibility — may be found in any part of the body. In such a 

 case, if anaesthesia corresponds with a region of a special nerve or mixed 

 nerve, or if it is extended over several nervous regions, or if it is 

 even double-sided, we can distinguish it as peripheric amesthesia. Periph- 

 eric anaesthesia indicates an injury of the terminal ends of the sensitive 

 nerves and originates through local influences, intense cold, acids (es- 



228 



