HORSE SICKNESS. 471 



ing might be, for the most part, ascribed to acute venous con- 

 gestion with exudation of blood plasma. This fluid, which is 

 either clear or more or less stained with blood, is found in large 

 quantities in the windpipe, pericardium, lungs, pleural cavities, 

 and other parts. In one case, seven pints of this fluid were 

 removed from the pericardium, but the amount as a rule is under 

 five pints. Although the blood is darker than usual, it does not 

 in any way possess the tarry appearance which is characteristic of 

 anthrax. It coagulates with extreme quickness. 



Whichever variety of the sickness the animal may have suffered 

 from, it is usual, though not an invariable rule, to find a huge 

 cloud of white foam around the mouth and nostrils of the dead 

 animal (see Fig. 14r5A, p. 467). This usually remains unchanged 

 to any great degree for a long time, even during exposure to a 

 hot sun. 



On making an incision into the subcutaneous tissue of the 

 neck, along the line of the windpipe, it is common to find lying 

 along, and in many cases surrounding the windpipe and the larger 

 vessels, a quantity of clear yellow jelly, consisting of blood serum 

 that has been pressed out of the vessels in this situation, and has 

 !!ubsequent]y undergone coagulation. If the windpipe is opened, it 

 will be found to contain yellow fluid in all stages of conversion 

 into the white froth noticed after death around the nose and 

 niouth. 



On opening into the large blood vessels in this area, the blood 

 will be found to contain clots, while the fluid between may be 

 slightly watery and is invariably of a very dark colour. 



On removing the front of the chest, the pleurae may be seen 

 to be occupied by a large amount of blood-coloured fluid. 



On the surface of the lungs it is common to flnd a layer, more 

 or less thick and diffused, of a yellow, gelatinous m^aterial, con- 

 sisting of coagulated blood serum. The lungs are as a rule pale 

 in colour, unless the animal has been severely ridden previous to 

 its death. On the surface will be noticed a large number of dark- 

 coloured lines which seem to pass over it and appear like small 

 rivulets. If slices of the limgs be m^ade with a knife and held up 

 to the light, it will be noticed that the lines in question are trans- 

 parent and of a yellow colour. They consist, in fact, of the yellow 

 serum, exuded in this situation, that has coagulated, and they 

 occupy the lines of division between the lobules of the lungs and 

 which in health ought to be scarcely apparent. In the dikkop 

 form, the chief sign is the swelling of the head, neck, or tongue. 

 In this form the lungs may be almost or absolutely unaffected 

 to the naked eye. 



The spleen as a rule is enlarged and deeply congested, and 



