Bed water in Cattle. 
207 
one whole year, as this probably exceeds the greatest possible 
lifetime of a tick which is denied the opportunity to suck the 
blood of an animal. Fortunately, however, there is a simpler 
and less expensive method of, so to speak, cleansing a pasture, 
and that is to graze it exclusively with horses or sheep for 
a full period of one year. Such a procedure does not lead to 
the extermination of the ticks, for these may maintain their 
existence and propagate their species on horses and sheep, but 
as only cattle can be infected with redwater, an infective tick 
ceases to be dangerous after it has attached itself to a sheep 
or a horse. It is to be hoped that in this country attempts will 
soon be systematically made to stamp out redwater by taking 
advantage of the facts just mentioned. It must be noted, how- 
ever. that an essential part of this plan is that after the full 
year has been allowed for the cleansing of the ticks, no animal 
of the ox species that has had an attack of redwater or which 
has even been grazed on redwater groiind must be allowed on 
the purified pasture, because, as already explained, such animals 
often for life contain the germs of the disease in their blood, 
and would therefore provide the means for re-infecting the ticks. 
Although the measures here advised can scarcely anywhere 
be altogether impracticable, it is obvious enough that in general 
a certain amount of loss and inconvenience would be caused 
in carrying them out, and it may therefore be asked whether 
there is any other means by which a farmer may prevent or 
reduce the loss which he annually suffers from redwater. 
That there is another method in reality follows from what has 
already been said, for it has previously been explained that the 
disease, when contracted in youth, is usually so mild as to be 
of little consequence to the animal and yet protects it for the 
rest of its life. Hence, where the more radical measures 
sketched above cannot be put into operation, a farmer may 
seek to minimise his losses by grazing the dangerous land 
exclusively with young cattle, or with cattle which have been 
for at least one season on such land. This plan is, however, 
not free from risk, for although an animal may have been 
grazed as a calf on dangerous tick-infested ground, it may have 
accidentally escaped infection and thus failed to acquire im- 
munity. The probable consequence would be that when this 
same animal I’eturned to the pasture next season it would 
contract the disease in a dangei'ous form. To counteract this 
risk the owner might assure the infection of his calves, or of 
such of them as were afterwards to be grazed on the dangerous 
pasture, by having them inoculated with the blood of an animal 
known to have recently recovered from an attack of redwater, 
as experience shows that this is an operation attended with 
little or no risk in the case of animals under six months old. 
