Cerebral HypercBniia. 91 



severe exertion during hot weather, in a violently contested 

 race, in drawing a heavy load up hill, or in harsh training. 

 Violent exertion just after a meal is especially injurious. Also 

 the excitement of travelling by rail, or that caused by proximity 

 to locomotives, to discharges of firearms and to other causes of 

 great fear ; encreased blood tension in the cerebral vessels in 

 connection with hypertrophy of the left ventricle, or obstruction 

 in other vessels (of the limbs) so as to direct the force of the 

 current into the carotids, the expulsion of blood from the 

 splanchnic cavities by gastric or intestinal tympany, or over- 

 loading of the paunch, and irritation of the brain by ptomaines 

 and toxins in certain infectious diseases (rabies, canine distem- 

 per, etc.) In the same way vegetable narcotics (opium, etc.) 

 produce congestion. Among the most common causes of con- 

 ge.stionare lead, poisoning by lolium temulentum, partially ripened 

 lolium perenne, millet, Hungarian grass, and partially ripened 

 seeds of the legumiuosse (chick vetch, vicia sativa.) Other 

 causes are the presence of tumors (cholesteatoma) and parasites 

 (coenurus, cysticercus) in the brain. 



Symptoms. Cerebral hypersemia, like other brain disorders 

 may give rise to a great variety of symptoms, according to the 

 condition of the animal and the susceptibility of its nerve centres. 

 Some cases have the characteristic seizures of vertigo, others the 

 manifestations of heat stroke, and others, epileptic explosions or 

 apoplectic symptoms. For these .see under their respective head- 

 ings. In other cases the symptoms are those of encephalo- 

 meningitis but moderate in its type and often tending to a transient 

 duration, or to prompt resolution and recovery. 



Horse. There is manifest change of the nervous and intellect- 

 ual conditions, which may show itself by irritability or restless- 

 ness, by pushing against the wall, by hanging back on the halter, 

 by trembling, sliaking the head, neighing, pawing and, in ex- 

 ceptional cases, by rearing, biting or kicking. The pulse is hard 

 and full, the heart's impulse strong, the beats in the carotids and 

 temporal arteries being especially forcible, and the buccal, nasal 

 and orbital mucosae are strongly congested. Heat of the head is 

 usually a marked feature. While usually very sensitive to touch, 

 noise or light, the animal may l)e dull or drowsy, and in spite of 

 its marked sensitiveness, it is then inert or lethargic and indis- 



