No. 6. DEPARTMENT OF AGRICULTURE. 149 



While forage is no doubt responsible for many of the outbreaks, 

 the actual pathogenic agent has not yet been discovered, thougU 

 a toxic mold or fungus is supposed to be the cause. All attempts 

 to find a specific raicro-organisni in the animals affected have failed 

 completely, nor has microscopic examination of the tissues revealed 

 any specific lesion. Gross examination usually shows hyperemia 

 of the brain and cord, and their meninges, with increase of fluid in 

 the subarachnoid spaces and ventricles. This fluid is clear, and 

 we have been unable to discover any micro-organism in it by cul- 

 tural methods. 



Symptoms. — The symptoms are referable to the central nervous 

 system. In mild attacks there is loss of control over the limbs 

 and tail, loss of appetite, and difficulty in swallowing. The inability 

 to swallow is often a marked symptom in more severe cases, and 

 the name "putrid sore throat" has been applied to the disease. 

 There is stupor, apathy, extreme muscular w^eakness, or actual 

 paralysis. A common symptom is contraction of the muscles of 

 the neck, back, and loins, with more or less opisthotonos. Par- 

 oxysms of delirium occur, during which the animal will push against 

 the wall, or show the disorderly movements due to meningeal irri- 

 tation. Coma and paralysis come on, and death occures in from 

 five to forty-eight hours. In most acute cases the animal falls 

 and dies in convulsions. 



It seems probable that several diseases which are characterized 

 by similar clinical sj^mptoms have been considered as one and the 

 same by observers. 



MacCallum and Buckley have found in the brains of horses dying 

 of this disease areas of softening "in the frontal region on each 

 side, anterior to the motor region of the cortex." This softening 

 was practically confined to the w^hite matter immediately under the 

 cortex, the rest of the brain showing no abnormality. In these 

 areas there w^as "complete destruction of the brain substance in 

 which the anatomical elements are disintegrated, and largely re- 

 placed by a colloid-like material." The neighboring blood vessels 

 were actually inflamed, with exudation of leucocytes, and passage 

 of the red corpuscles into the peri-vascular lymph sheath and adja- 

 cent tissues. In a second outbreak they failed to find the softened 

 areas in the brain, but the condition of the blood vessels was such 

 as to make them believe that they had the earlier stages of the 

 same process. They have given the name "Acute Epizootic Leu- 

 coencephalitis." (Bulletin 80 of the Marland Agricultural Experi- 

 ment Station.) 



The disease has engaged our attention at the laboratory of the 

 State Live Stock Sanitary Board for several years, and examina- 

 tion by cultural methods have been made whenever possible, but 



