140 THE PRACTICE OF VETERINARY MEDICINE. 



horse, but oftener in highly bred cattle. The symptoms 

 are those of cerebral disturbance as ordinarily manifested. 



Thickening of the Dura Mater. — This condition is of rare 

 occurrence, but occasionally is met with both in the horse 

 and the ox, causing partial absorption of the cranial 

 bones, and even of the brain substance. The hard 

 structures we find, as a rule, yielding to the soft structures. 

 The symptoms are those of brain disease. No treatment 

 is of any avail. 



Atrophy of the Brain. — This condition is rare, and, like 

 hypertrophy, when it does occur, it is usually as a sequel 

 to some one or other of the many diseases affecting the 

 Ijrain. 



Hypertrophy of the Brain. — This disease usually occurs 

 in connection with the meninges of the brain, although the 

 brain itself occasionally becomes enlarged. 



Tumours. — Osseous tumours and melanotic tumours some- 

 times form in the brain substance. Melanotic tumours are 

 composed of pigmentary matter, and occur oftenest in grey 

 or white horses, and may form in any tissue of the body. 



Symptoms. — Dulness on the part of the patient. He is 

 subject also to sudden attacks of convulsive fits, and in 

 many cases the patient, when left to himself, shows an in- 

 clination to seek the most elevated spot accessible. If the 

 tumour exists in connection with the medulla, the animal 

 will often, without warning, drop to his knees as suddenly 

 as though struck by lightning. This condition and the 

 similar ones previously described give rise to about the same 

 general symptoms, and, like atrophy and hypertrophy of 

 the brain, this condition is incurable. 



Softening of the Brain. — This is a very rare condition in 

 the horse, but it does occasionally occur, and when it does 

 it is usually as a result of epizootic cellulitis. The disease 

 may occur as a result of many other causes with which we 



