KEMARKS ON THE CATTLE DISEASES. 165 



difficult it is in licaltliy animals to cause any great deviation from a nor- 

 mal standard, even during the hottest days of a western summer. Com- 

 parative observations on a number of animals at the same time consti- 

 tute a valuable and essential test. It was, however, striking and strange 

 that in examining Texan cattle caught with the lasso, the temperatures 

 obtained were the same as those among work cattle of the same herds, 

 and which could be handled readily near the wagons. Observations of 

 this kind are referred to in the report on splenic fever. 



The best part — and only one which should be chosen — for the insertion of 

 the thermometer, is the rectum. The instrument must be introduced as 

 nearly as possible to the same extent in all cases, and retained in situ at 

 least three minutes. Animals are apt to defecate soon after the ther- 

 mometer is passed in, and the rectum then remains passive for a time. 

 This necessitates the withdrawal and reintroduction of the instrument, 

 and the time required for the observation must be taken from the sec- 

 ond intromission. 



By this means animals in apparent health, grazing and moving in 

 perfect comfort, are often found sick ; and in the case of a contagious 

 disease like pleuropneumonia, this timely warning- is of the highest 

 moment. 



In relation, however, to the nature of a malady, much is taught us by 

 the thermometer. The periodic fever of southern cattle begins, like the 

 rinderpest, with an increased heat of the body. The local changes ap- 

 pear secondary to the general fever, though it is difficult to estimate the 

 time that elapses from the flrst exaltations of temperature to the local 

 manifestations. In pleuro-pneumonia it is probable, and indeed our 

 observations are almost conclusive on the point, that there is first a local 

 change and commencing- deposit. A material grows and penetrates, 

 charged with and dependent on the presence of a specific poison, and 

 when it has sufficiently involved any important parts and become com- 

 plicated with ordinary inflammatory changes, the general fever sets in. 

 An elevated temperature is, however, observed in this disease long before 

 a farmer or dairyman suspects that an animal is affected. This is the 

 only Avay in which some latent cases of pleuro-pneumonia are recognized. 



Scientific men have hitherto fiiiled in tracing the distinctive charac- 

 ters of organic poisons which differed from each other, and only recog- 

 nized by the very different effects produced on the animal economy. 

 Some attack a single species of animal; others induce the same disease 

 in a number of species. The lung-plague poison induces its character- 

 istic effects on cattle ; the poison of hydrophobia, most readily commu- 

 nicated among feline and carnivorous animals, is deadly to the omnivora 

 and vegetable feeders. Of the peculiar principles which tend to the 

 diffusion of those diseases which are known to us as indigenous in cer- 

 tain latitudes, and which we must disting-uish at all times, in classifying 

 diseases, from the contagious maladies of no known ])rimary source, we 

 have two equally remarkable instances in the splenic fever of the south, 



