EXAMINATION OF A SICK HORSE. 25 



nation, of movements. Disturbances of the cerebellum cause a totter- 

 ing, uncertain gait. In the medulla oblongata, which lies between the 

 spinal cord and the cerebellum, are the centers governing the circula- 

 tion and breathing. 



The spinal cord carries sensory messages to the brain and motor 

 impressions from the brain. The anterior portions of the cord con- 

 tain the motor paths, and the posterior portions of the cord contain 

 the sensory paths. 



Paralysis of a single member or a single group of muscles is known 

 as monoplegia and results from injury to the motor center or to a 

 nerve trunk leading to the part that is involved. Paralysis of one- 

 half of the body is known as hemiplegia and results from destruction 

 or severe disturbances of the cerebral hemisphere of the opposite side 

 of the body or from interference with nerve paths between the cere- 

 bellum, or small brain, and the spinal cord. Paralysis of the poste- 

 rior half of the body is known as paraplegia and results from de- 

 rangement of the spinal cord. If the cord is pressed upon, cut, or 

 injured, messages can not be transmitted beyond that point, and so the 

 posterior part becomes paralyzed. This is seen when the back is 

 fractured. 



Abnormal mental excitement may be due to congestion of the brain 

 or to inflammation. The animal so afflicted becomes vicious, pays no 

 attention to commands, cries, runs about in a circle, stamps with the 

 feet, strikes, kicks, etc. This condition is usually followed by a dull, 

 stupid state, in which the animal stands with his head down, dull and 

 irresponsive to external stimuli. Cerebral depression also occurs in 

 the severe febrile infectious diseases, in chronic hydrocephalus, in 

 chronic diseases of the liver, in poisoning with a narcotic substance, 

 and with chronic catarrh of the stomach and intestines. 



Fainting is a symptom that is not often seen in horses. When it 

 occurs it is shown by unsteadiness of gait, tottering, and, finally, in- 

 ability to stand; The cause usually lies in a defect of the small brain, 

 or cerebellum. This defect may be merely in respect of the blood 

 supply, to congestion, or to anemia, and in this case it is likely to pass 

 away and may never return, or it may be due to some permanent 

 cause, as a tumor or an abscess, or it may result from a hemorrhage, 

 from a defect of the valves of the heart, or from poisoning. 



Loss of consciousness is known as coma. It is caused by hemor- 

 rhage in the brain, by profound exhaustion, or may result from a 

 saturation of the system with the poison of some disease. Coma may 

 follow upon cerebral depression, which occurs as a secondary state 

 of inflammation of the brain. 



Where the sensibility of a part is increased the condition is known 

 as hyperesthesia, and where it is lost — that is, where there is no feel- 

 ing or knowledge of pain — the condition is known as anesthesia. The 



