272 CHAPTER 31. 



decomposes, and gas is quickly formed and evolved. In the early stage 

 this may probably be carbonic acid gas, and in the latter or putrefactive 

 stage, sulphuretted hydrogen. 



The pulse in the comatose stage of stomach staggers is below the 

 normal number, sometimes as low as twenty beats in the minute. The 

 respiration is also slower than usual. But when the disease runs on to 

 mad staggers or encephalitis, the pulse and respiration become quickened 

 and excited, as described hereafter. 



551 . Connection hetween the Stomach and the Brain. 



There are two theories as to the reason why indigestion, when accom- 

 panied with distension of the stomach, affects the brain. 



The branches of the Par vagum or Pneumogastric nerve, ramify over 

 the stomach, lungs and heart. When the stomach is distended, this 

 nerve is unduly and continuously pressed upon, and so gets into a torpid 

 state ; and the lethargic symptoms of comatose staggers are supposed to 

 be the result, by reflex nervous action of the brain. 



Others think that the distension of the stomach prevents the action of 

 the diaphragm and the proper extension of the chest in inspiration. 

 Hence the blood is insufficiently purified, and the vital fluid supplied to 

 the brain is more or less impure. Hence also there is decreased power 

 and consequent torpidity of circulation ; for these results depend on 

 nervous tone and power ; and from these causes, it is thought, arises 

 Coma. The former, however, is the more probable explanation. 



652. Symptoms of Mad Staggers, Encephalitis, and Phrenitis. 



Mad Staggers may, as stated above, be a sequel of the comatose state ; 

 but occasionally the disease develops itself without any such preliminary 

 sleepy symptoms. Restlessness suddenly appears, followed by a violent 

 state of excitement and delirium. The patient paws with his feet, per- 

 spires freely, and stares about with wildness and vacancy of countenance. 

 The respirations are quickened and excited. Febrile symptoms increase. 

 The mouth becomes hot and dry, the nasal and conjunctival membranes 

 are much injected, and the pulse is strong and sharp, often reaching as 

 high as 80 or 90, or even 120 beats in the minute. The animal throws 

 himself about madly, gets his feet in the manger, tears the rack with his 

 teeth, and breathes stertorously, with his eyes apparently staring out of 

 their sockets. The pupils are fully dilated, no light will affect them, nor 

 is the horse sensible of surrounding objects. Some hard dry dung 

 pellets, or a small quantity of highly coloured urine may be passed. 

 There is spasmodic contraction of the muscles. 



Alternately with the violent fits periods of repose and drowsiness often 

 occur, and the animal stands exhausted and sweating at every pore, with 

 his head bored into a corner. During such intervals the pulse is almost 

 in a state of collapse. The violent fits come on more and more quickly, 

 until the animal is in a continuous struggle, panting and perspiring and 



