DISEASES OF THE NERVOUS SYSTEM. 499 



standing tliese varieties in the temperament and intelligence of 

 animals, tlie purely mental — psychological — diseases are absent 

 in our patients. 



EPILEPSY. 



A peculiar nervous state, difficult to define, but in which 

 complete loss of consciousness prevails for a short time, associ- 

 ated with spasmodic contractions of the muscles, succeeded by 

 debility, and sometimes by a desire to sleep. Epilepsy occurs 

 amongst all animals, but is most commonly seen in young dogs. 



The pathological condition of the brain which gives rise to 

 epileptic fits is not yet determined; indeed, in fifteen out of 

 twenty cases in which the brains of epileptic human patients 

 have been examined, the structure of the brain has been found 

 quite healthy. Occasionally, however, the brain and its mem- 

 branes are actually diseased ; thus the membranes may be found 

 thickened, inflamed, or even ossified. In one horse, subject to 

 epileptic fits, an abscess in the white matter of each hemisphere 

 was found by me ; in another, tumours in the choroid plexus ; 

 but in some instances it is due to some condition of the blood, 

 as in those fits which are associated with catarrhal fever. In 

 young dogs epileptic fits are associated with dentition, and with 

 worms in the intestinal canal or stomach. 



Dr. Brown Sequard's researches into the origin of epilepsy are 

 quoted at length by Mr. Gamgee in his Domestic Animals in 

 Health and Disease, page 458. They are very interesting, but 

 the tendency at present is to consider epilepsy certainly as a 

 brain disease, but as one in which no definite pathological condi- 

 tion can in all cases be determined ; and that the loss of con- 

 sciousness, associated with excessive mobility, leads observers 

 to regard those parts of the brain in the immediate vicinity of 

 the cella turcica and basilar portion of the occipital region — for 

 example, the central ganglia or medulla oblongata — as parts 

 where, in future, morbid anatomy may yet discover a lesion. 



Sym2:>toms. — An animal in apparent health is seen to stagger 

 and stare — the dog cries out at first, but is afterwards quite 

 dumb — and then to fall into more or less violent convulsions, 

 the whole system being agitated. The urine and faeces are some- 

 times passed involuntarily, the eyelids are closed, and if they 

 are opened and the eyes examined, they will be seen to be in- 



