DISEASES OF THE NERVOUS SYSTEM 409 



slight concussion, or may even result in the depression of some of the bones 

 forming the cranial cavity, in which case stupor will result, and will con- 

 tinue until the depressed portions of bone are elevated by means of a 

 surgical instrument. 



When the injury is slight, the fit of giddiness which follows generally 

 passes off in a short time and leaves no trace behind; but the rider or 

 driver, being probably unaware that the animal has been struck on the 

 head, is disposed to look upon the attack as a case of megrims of the 

 ordinary kind. The fact, however, of the attack not recurring would be 

 a sufficient evidence that the injury is not permanent. 



Treatment. — As the occurrence at irregular intervals of fits of vertigo 

 is at the least annoying, and cannot be said to be unattended with danger 

 to the rider or driver, it is naturally a subject of enquiry as to what can be 

 done in the way of prevention. If any positive cause, such as a tight collar, 

 is detected, the remedy is of course perfectly obvious. Should symptoms of 

 disease of the liver be present, a dose or two of aloes with calomel may be 

 given with benefit; but if there is no obvious cause, the conclusion will 

 necessarily be that there is some morbid condition of the central nervous 

 system, and beyond attending to the animal's general health by judicious 

 feeding and properly regulated work or exercise, nothing can be done. 

 Horses suft'ering from chronic brain disease should never be hurried or 

 called upon to undergo severe exertion. Moreover, they should be fed two 

 or three hours before being employed in any kind of work, and food should 

 be given in small quantities and often. 



ABSCESS IN THE BRAIN 



A more serious result of a blow on the head is the formation of abscess 

 in one of the hemispheres of the brain, or inflammation of the membranes, 

 which is usually indicated by violent excitement. Abscess in the brain also 

 occurs not uncommonly when, in consequence of a vessel being punctured 

 in the act of opening an abscess, a quantity of pus may get into the blood- 

 stream, causing the condition which is known as pycBmia. Abscesses in 

 various parts of the body are the result of this contamination of the blood, 

 and the brain is a very favourite situation for the deposit of pus. The 

 first indication of the occurrence is the appearance of drowsiness, gradually 

 increasing to unconsciousness, in which condition the animal dies. No 

 treatment is likely to be of any avail. 



