558 DISEASES OF THE HOBSE. 



a slight partial paralysis, and the hind quarters of the animal reel 

 from side to side. In connection with this it may be noted that there 

 is frequently present paralysis of the sphincter ani and a dilated 

 condition of the anus. These symptoms taken together point to some 

 interference with the normal functions of the spinal cord in the lower 

 dorsal and lumbar regions, and are probably due to pressure caused 

 by an exudation within the spinal membranes. In many cases shortly 

 before death the heart's action becomes exceedingly violent, shaking 

 the whole frame at each beat, so that the sound can be heard at some 

 distance from the animal. In some of these cases the animal may 

 suddenly drop dead ; in others the emaciation and weakness become 

 so pronounced that the animal falls to the ground, and, after a short 

 struggle, succumbs to the disease. In other cases, again, the animal 

 falls to the ground and appears to be suffering from acute pain, 

 struggles violently, sweat covers the body, and respiration is very 

 hurried. The struggles soon exhaust the patient's strength, and for 

 a time it lies quiet; soon, however, the struggles conunence again, 

 and this continues until death occurs. In some cases the appetite is 

 voracious. 



The symptoms of the disease as observed in experimentally inocu- 

 lated animals are as follows : Twenty-four hours after the subcutane- 

 ous injection of a small quantity of surra blood, in the great majority 

 of caseSj a small circumscribed and somewhat raised swelling is 

 noticed at the seat of the inoculation. After forty-eight hours the 

 tumor has increased in size and is accompanied by some edema; it 

 presents a certain amount of tension of the parts involved, and is 

 generally tender on manipulation. These conditions continue to in- 

 crease, until by the fourth day the tumor may measure 3 or 4 inches 

 in one direction by 2 or 3 in the other, and raised to the extent of an 

 inch or an inch and a half above the surrounding tissues, or in some 

 cases the tumor presents an almost circular form throughout. It will 

 be also found that, if the tumor be firmly grasped, it is not fixed, but 

 can be lifted up from the subcutaneous tissue. According to the 

 nature and amount of the inoculated blood, these symptoms rapidly 

 present themselves, and either attain a maximum or. are retarded 

 until, varying from the fourth to the thirteenth day, the tumor at 

 the seat of inoculation will be found to have lost a certain amount 

 of its tension and tenderness. From this date the swelling and edema 

 will gradually begin to grow less, until finally^ after a period of ten 

 to fourteen days, the only sign left of the former swelling will be 

 slight thickening of the skin over the point of the injection ; but at 

 the moment when the tension and tenderness of the parts at the seat 

 of inoculation become suddenly decreased a symptom of the utmost 

 clinical importance takes place, namely, at that moment the parasite 

 of surra enters the blood of the general circulation. 



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