LOCOWEED DISEASE OF SHEEP 375 



A. INFORMATION OBTAINED FROM THE RANCHMEN AND FROM THE 

 LITERATURE. 



The spread of loco disease. Inasmuch as Marsh* and Crawfordf have 

 published elaborate bibhographies and historical reviews of locoweed 

 disease, only special features will be selected for remark here. It seems 

 probable from such information as can be obtained that loco disease 

 ,\vas first observed in Mexico or Texas, and thus received its Spanish 

 name of "loco" or "crazy" disease. It was known in the seventies in 

 California; about the same time in Texas and Colorado; a few years later in 

 AVyoming, and apparently it was first observed in Montana about 1884, 

 when Jacob Severence described "loose-teeth lambs." Its general recog- 

 nition in ]\Iontana dates from about 1890. It seems probable that loco 

 disease spread northward from Mexico, the disease becoming notable 

 in each locality ten, twelve, or fifteen years after the ranges were first 

 occupied by live stock. Apparently a very large part of the live stock of 

 the West is descended from old Mexican stock, the animals having bpen 

 tlriven further and further north as fresh ranges were needed. 



Definition. The general opinion in the West is that locoweed disease 

 is a definite form of drug poisoning produced by the locoweed in animals 

 which have formed the habit of eating the weed. Most ranchmen believe 

 that the whole plant is poisonous, a few hold that the poison resides in the 

 flowers, a large nvunber consider the roots to be the. most dangerous part 

 of the plant. Some believe that one variety of locoweed is more dangerous, 

 others, another. 



A small number of ranchmen reject the view that the locoweed is poison- 

 ous. Most of these men believe that the craving for the locoweed prevents 

 animals from eating a sufficient quantity of nutritious food, and that the 

 s\-mptoms are those of starvation. Others contend that the locoweed is 

 of itself altogether harmless, and that the symptoms are caused by some 

 worm or other parasite residing in the locoweed. A very small number 

 believe that all cases of "locoweed disease" are in reality examples of 

 other diseases, such as starvation, or parasitic infection. 



The locoweed. There is some confusion as to the identity of the loco- 

 weed. Many other plants have been called locoweed, and there is no 

 tloubt that many cases of poisoning bj^ other plants have been looked 

 upon as cases of locoweed disease. The botanical characteristics of the 

 various locoweeds have been given in Bulletins 20 and 26 of the Depart- 



* Bureau of Animal Industry, Bull. 112, 1909. 

 t Bureau Plant Industry, Bull. 129, 1908. 



