Diagnosis. 669 



increase in severity so qnickly that the animal dies in the course 

 of a few days. This stage, as a rule, lasts from two to six 

 weeks, but it may extend, and especially in cattle, to two to 

 three months, or even longer. Gieres records a case in which 

 it was eight months; and Pfab, one in which it was more than 

 a year. 



Death is generally due to weakness and anemia, but it is 

 sometimes quite sudden and resembles apoplexy. 



Diagnosis. During the acute stage the symptoms are those 

 of acute cerebro-meningitis, and during the chronic stage those 

 of increased intracranial pressure. An option as to the cause 

 of the increased pressure may be based upon the local symp- 

 toms, the examination of the roof of the cranium, and the fur- 

 ther course of the disease, provided the preliminary enquiry 

 affords exact information. In the absence of such information, 

 diagnosis passes beyond the bounds of possibility, although in 

 practice the disease is generally easily recognized, and espe- 

 cially in the sheep, on account of its frequent occurrence and 

 still more from the postmortem examination of some of the 

 animals. 



In connection with differential diagnosis, sunstroke and 

 acute meningitis must be taken into consideration. Apart from 

 the sudden onset of the disease, these cause severe depression 

 from the outset. Forced movements and particularly move- 

 ments in circles are only rarely observed. There is congestion 

 of the mucous membranes of the head, and the course is very 

 acute. When the disease occurs enzootically among sheep, it 

 may be confounded with infectious cerebro-spinal meningitis, 

 especially when housed animals are attacked. Apart from the 

 diagnostic symptoms of meningitis, a diagnosis may be always 

 based upon a postmortem examination. Severe cerebral symp- 

 toms may be caused in sheep by the larvas of the CEstrus ovis. 

 In such cases, there are only symptoms of acute inflammatory 

 disease of the brain and its meml)ranes without forced move- 

 ments, and besides valuable information is furnished by the ca- 

 tarrh of the nasal cavities and sinuses which is present at the 

 same time. One must not lose sight of the fact that both dis- 

 eases may exist at the same time. Errors should scarcely be 

 made in other cases of catarrh of the nose and sinuses. 



Tumors of the brain, tuberculosis of the brain, or its mem- 

 branes in cattle and in particular echinococcus cysts may set 

 up similar sjmiptoms. 



In such cases the possible presence of similar tumors, tu- 

 berculosis, or parasites in other organs, aifords a certain 

 amount of information, although this does not enable one to 

 make a certain diagnosis. With regard to tuberculosis, the 

 presence of lesions in the eye is decisive. For the rest, atten- 

 uation of the roof of the cranium has not up to the present 

 been observed in anv other disease of the brain. In the horse 



