CEREBRO-SPINAL MENINGITIS. 
409 
believes that it probably prevailed as an enzootic in the Indian 
Territory a few years since. Thus at present we cannot accu¬ 
rately lay down its geographical limits; probably it occurs in the 
sporadic form in nearly all countries; it is only in the United 
States as yet, that the disease has taken on an epizootic character. 
The tropical regions proper have hitherto escaped its ravages in 
the human subject, and are believed to be exempt; perhaps the 
same may hold good of the horse. 
Etiology .—Its etiology is enshrouded in mystery ; age and 
extreme conditions of life, which have so powerful an influence 
in the human subject, exert no appreciable effect in the horse; it is 
met with alike on high plateaus and marshy lands; in some out¬ 
breaks mares seem to be more susceptible than geldings, but just 
as likely as not in the next run of cases, this state of affairs is 
reversed. Atmospheric influences have been called in to account 
for its development in the epizootic form, and may possibly be 
concerned in the distribution of the virus. Though isolated cases 
may be met with at any season of the year, it is essentially a dis¬ 
ease of the cold months. It has been pointed that the most severe 
outbreaks take place in early spring, when the sun is warm enough 
to thaw the ground during the day, and so release the poisonous 
germs, but the weather still too cold to allow of the stable doors 
and windows being left open for ventilation; this state of affairs 
causes a great accumulation of poisonous matter in the stables, 
which produces its results in due time. In the Canadian outbreak, 
Urofsssor Smith traced the cause to impure water; on remedying 
this, no more animals died, but next year, after watering at the 
same place, the disease again appeared. This appears to be con¬ 
clusive evidence that it may be produced as a dietetic disease, 
and most probably a great many sporadic or localized outbreaks 
might be found to have a similar origin. In the November num¬ 
ber of the Arnei'ican Veterinary Review , is an article by Dr. 
Michener, of what is, in his locality, called “ choking distemper,” 
and also by some, convulsive ergotism. In this particular in¬ 
stance, over forty horses were fed on some brewers’ grains, and 
every one died from the disease ; on being fed to cows, these 
grains did not produce any deleterious effects; he also mentions 
