Diseases of Vie Nervous System 195 



Heat Prostrations 



In very warm weather heat prostrations may occur, 

 especially among heavy fowls. This is sometimes considered 

 to be the same thing as apoplexy. The birds suddenly drop 

 insensible or paralyzed. 



Etiology. — The cause is pressure on the brain, due to heat, 

 but the blood vessels are not ruptured as in apoplexy. 



Treatment. — Mild cases may be treated by applying cold 

 water to the head and keeping the bird in a cool, quiet place. 



Prognosis. — Mild cases may recover. Others usually 

 result fatally in a short time. As a preventive avoid over- 

 crowding in hot weather. If the range is not provided with 

 natural shade, supply artificially shaded places in which the 

 birds may find protection from the hot sun during the middle 

 of the day. 



Congestion of the Brain (Vertigo, Cerebral Hypercemia) 



A number of abnormal physiological conditions may lead to 

 a congestion of blood in the brain. This is usually associated 

 with a diseased condition of other organs, and hence often 

 occurs as a complication with other diseases. It is some- 

 times due to injury of the head. 



Diagnosis. — Pearson and Warren ^ give the following 

 diagnosis of this disease : " It is characterized by stagger- 

 ing, stupor, unusual movements such as walking backward 

 or walking in a circle, unusual and irregular movements with 

 the wings and feet and twisting the head backward or to the 

 side. Sometimes the bird will fall on its side and make 

 peculiar movements with its feet and wings as though 

 attempting to run or fly." 



1 Pearson and Warren, "Diseases and Enemies of Poultry." 1897. 



