TEXAS FEVER 333 
exposure of susceptible cattle to the development of the disease 
depends on whether or not the whole life cycle of the tick must be 
passed or part of it has already gone by. If susceptible animals are 
placed in a pasture where the young ticks are just ready to crawl upon 
them the infection of the cattle is accomplished at once and the high 
fever appears in about ten days, practically the minimum time. It 
has been experimentally demonstrated that the young ticks are able 
to travel for a considerable distance in a pasture. In pastures where 
tick infested cattle are grazing, young ticks are very liable to be on 
the ground continuously. In estimating the time to elapse after the 
exposure to the tick infested animals or field, before the disease will 
appear, it is necessary to know in what stage in the life cycle the ticks 
are at the time when the susceptible animals come in contact with 
them. Cattle have been exposed in feeding pens to young ticks that 
had hatched from eggs laid by adult ticks left in the yards some time 
before by infested cattle and developed the disease ten days after 
exposure. 
Small quantities of the blood from immunized cattle in the tick 
infested district, when injected into susceptible animals either 
intravenously or beneath the skin, will produce the disease. While 
this mode of infection rarely if ever occurs in the natural order of 
events, it may happen that in cases of certain operations bits of blood 
may be carried directly from a southern to a northern animal thus 
inoculating the latter with the disease.* 
Symptoms. In the acute type of the disease which occurs during 
the hot summer months, the onset is sudden and usually all animals 
exposed to the same infection together come down at the same time. 
The first indication of the disease is a rise of temperature, at first 
higher in the afternoon than morning, but later in the course of the 
disease the temperature remains high. It rarely rises above 107° F. 
The rise of temperature occurs two or more days before there are other 
symptoms. The respiration may rise to between 60 and 100 and the 
pulse may range between 80 and 100 per minute. Late in its course 
*In the fall of 1898 two cases occurred in the practice of Dr. Ambler of Chatham, 
N.Y. The owner had his animals dehorned in December and soon afterward two fatal 
cases of Texas fever developed. The Piroplasma and the characteristic lesions were 
present. Inquiry revealed the interesting fact that the two animals which sickened 
and died were dehorned immediately after two imported southern cattle. The owner 
was not aware of the fact at the time that these were southern bred cattle, as he had 
bought them of a dealer in Vermont. More recently another case of this disease pro- 
duced in the same way has been reported. 
