234 DISEASES OF THE NERVOUS SYSTEM 



or some disease of the I)rain. They may also occur from disorder of the 

 spine. These so-called cataleptic attacks consist of a rigid and contracted 

 condition of all the muscles of the body, but are subject to passive move- 

 ments. Nothing is known concerning their etiology. Tetanic convul- 

 sions are tonic convulsions of the whole muscular system of the body, 

 They appear in tetanus and in some cases of poisoning (strychnine, 

 brucine, caffeine, etc.). A variety of these tetanic convulsions is some- 

 times observed in the so-called cases of eclampsia in bitches who are 

 nursing a large litter of puppies. Forced irregular actions of the body, 

 such as walking backward or in a circle, or the animal rotating on its 

 own axis, are seen as a rule in diseases of the cerebellum and in some 

 cases of poisoning (cocaine). In rare instances we see, in the above 

 mentioned, symptoms of '' ej^ileptif orm attacks," w'hich we will refer to 

 further on. 



Ataxia is due to disturbance of motility or an interference in the co- 

 ordination of muscular action. Animals are unsteady on their legs, 

 stagger from one side to another, and their action in walking is irregular. 

 Ataxia is undoubtedly found in some diseases of the cerebellum, and may 

 also be seen in disease of the pons and the fore ventricles, and, in very rare 

 instances, of the spinal cord. Ataxia occurs very often as a result of dis- 

 temper, and it occurs without any previous brain or spinal symptoms. 



Concerning disturbances of vision, hearing and the action of the 

 sphincters, they will be described under their special chapters. 



Disturbance of Reflex Irritability. — Reflex action is those movements 

 that arc caused by some stimulus or irritation that produce a movement 

 that is entirely independent of the will, unless the will is concentrated to 

 oppose the movement. In this instance we call particular attention to what 

 is known as patellar reflex. The animal is laid on his side with the hind 

 leg to be examined on the upper side, the leg is slightly flexed and with 

 the index finger or a percussion hammer a cpick blow is made on the 

 patellar ligament below the patella; under normal circumstances the 

 quadriceps femoris muscle makes a quick contraction, the muscles of the 

 leg contract and the leg is sprung forwards. The same reflex but to a 

 lesser extent is also seen at the anterior face of the carpal articulation, the 

 Achilles tendon, skin of the sole of the foot and the abdominal wall. An 

 increase of the reflex is seen in the course of chronic diseases of the brain, 

 in myelitis transversalis, spinal paralysis (first observed by Dexter) pois- 

 oning with strychnia, tetanus. A diminution of the reflex is sometimes 

 found in acute diseases of the lirain, which have been verj' rapid in their 

 development, in certain diseases of the spinal substance, in disease of the 

 peripheric nerves (in which case it is confined to the territory of the corre- 

 sponding nerve) and in coma. The brain reflexes to be particularly con- 

 sidered are the conjunctival and corneal reflex seen by the closure of the 



