BUEEAU OF ANIMAL INDUSTEY. 259 



did opportunity for transmission if such were possible. The cow 

 died in an extremely emaciated condition about three months after 

 her arrival, and the post-mortem examination revealed no lesions 

 except the characteristic changes in the mucosa of the intestines. 

 These changes were particularly marked in the ileum. The exposed 

 chickens were killed after the death of the cow and were examined. 

 They showed no lesions whatsoever, and mucous scrapings from 

 different portions of the intestines failed to demonstrate the presence 

 of acid-fast organisms. The histological examination of the affected 

 intestines from the cow showed changes characteristic of the disease, 

 the specific organisms being present in the mucosa and contiguous 

 lymph glands in numerous clumps. Attempts to grow the organism 

 on various culture media failed to give satisfactory results. 



BIGHEAD OF SHEEP. 



The disease of sheep known to flock masters of certain sections of 

 the intermountain regions of the West as '• bighead " has been the 

 object of investigation in an effort to learn something of its nature 

 and cause. On account of the fleeting character of the disease and 

 its entire absence in certain years a good opportunity to study it 

 has not heretofore been afforded. However, a number of cases were 

 seen this year by a member of the staff of the Pathological Division, 

 and it is thought that a correct insight of its nature has been obtained. 



The localities where this disease is known range in altitude from 

 4,500 to 8,000 feet above sea level, usually on the plains and valleys 

 between the higher ranges of mountains. Places are known in Idaho, 

 AVyoming, and Utah where it is likely to make its appearance during 

 any of the spring months. It is most often seen in the spring follow- 

 ing the melting of the snows or immediately after late snowstorms 

 at that time of the year. As indicated by its name, the chief and 

 characteristic symptom is a very much swollen condition of the head. 



A singular feature about this disease is that it is usually confined 

 to certain bands, and that quite a number of animals are simultane- 

 ously affected. It occurs only in certain regions of the West, and 

 with more or less yearly regularity, varying, so the stockmen claim, 

 with climatic conditions. There appear to be very definite localities 

 where it is looked for by herders on the trail. The soil of all these 

 regions is of volcanic formation. The flora is also more or less simi- 

 lar, and the climatic conditions are likely to be very much alike. 



Post-mortem examinations did not give much information as to 

 the cause. Aside from the edematous infiltrations of the subcutaneous 

 tissues of the liead and certain alterations or destruction of the eyes 

 nothing very abnormal was found. From the internal organs of 

 five affected animals culture media were inoculated in an effort to 

 isolate any disease-producing micro-organisms that might be har- 

 bored therein, but in no case was a growth obtained except from 

 accidental contaminations from the air. 



From the histories of various outbreaks of the disease, as related 

 by a number of intellijient and observing sheep owners and from 

 personal observations, it is certain that many views previously held 

 as to its etiology are wrong. For instance, it does not require 

 a storm to produce the disease; it does not require melting snows 

 to bring on an attack; alkali water does not cause bighead in 



