212 DISEASES OF THE BBATN 



are indicated. In small animals the electric battery may be 

 useful. In chronic cases only a successful treatment of the 

 basic disease will heal the brain anemia. 



CONGESTION OF THE BRAIN AND ITS MEMBRANES. 



Brain congestion may be active, due to an engorgement of 

 the brain with aterial blood, or it may be passive, caused 

 by a stoppage of the outflow of venous blood. 



Etiology. — Passive congestion rarely produces symptoms in 

 animals. An active hyperemia of the brain can be caused 

 by an increased heart activity and the loss of tonus in the 

 cerebral arteries due to overwork, rough treatment of young 

 animals (breaking colts; the excitement of railway or ship 

 transportation); estrum; fright; hypertrophy of the heart"; 

 acute alcohol poisoning; sun- and heatstroke. A collateral 

 congestion may result from compression of the large blood- 

 vessels of the abdomen in severe bloating of the stomach or 

 bowels. An active hyperemia of the brain is the first stage 

 of inflammation. 



A passive hyperemia occasionally occurs from compression 

 of the jugulars from ill-fitting collars, too tight throat latches 

 ("choking down" of horses), tumors, inflammatory swellings 

 or enlarged thyroids which press upon the jugulars. It may 

 also be a symptom of heart weakness, chronic diseases of 

 the lung, or compression of the lung from gas accumulation 

 in the stomach or bowels. 



Symptoms. — The symptoms of active hyperemia are those 

 of excitement, which usually is soon followed by a stage of 

 depression. The pupils are dilated, the mucous membrane of 

 the head congested, the pulse and respirations are increased 

 in frequency, and the poll feels warm. Very probably, how- 

 ever, these symptoms represent a transient inflammation of 

 the brain, often the result of a chronic hydrocephalus, which 

 occasionally "flares up" in this form. 



, A severe passive hyperemia causes the animal to show 

 stupor, sopor, the mucous membranes cyanotic, the pulse 

 small and rapid, and the patient dyspneic. 



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