OF VETERINARY MEDICINE. 27 



of the leg is not sufficient and congestion occurs producing lame- 

 ness. Severe exercise would have caused gangrene if the horse 

 had not become so lame that he could not go any further. 



An ante-mortem clot is light colored ; a post-mortem clot is 

 black. In making a post-mortem we often "find in the cavities 

 of the heart a clot resembling chicken fat, lodged among the 

 valves, — a soft and friable mass. The remaining portions of 

 the cavities are filled with black clots. The chicken fat clot is 

 formed before death; it varies in color and density, from a soft 

 yellow substance to a fibrinous grayish mass. The old ante- 

 mortem clots are usually found in the posterior aorta or in the 

 iliac arteries. They are more or less hard and somewhat elastic, 

 rather filling the vessels. The degree of hardness indicates their 

 time of formation. Very hard clots may have formed months 

 back, even years perhaps. An ante-mortem clot consists of 

 fibrin, leucocytes and some few red blood corpuscles, which fade 

 out. 



A post-mortem clot consists of all the elements of the blood 

 and if the coagulation is rapid is of a dark red or black color. 



An IRRITANT is anything that produces a local disturbance pri- 

 marily and a constitutional disturbance secondarily. It is a sub- 

 stance which when applied to a part causes a greater or less de- 

 gree of vascular excitement. The stimulating influence of an 

 irritant may simply alter the function of the part, it may pro- 

 duce marked congestion and it may result in inflammation. 



The effects of local irritants are usually the same as in active 

 congestion, — redness, swelling, heat and pain. The topical signs 

 are the same also. 



It is the action of an irritant to stimulate, but the various 

 irritants do this in different ways. For example, alcohol in- 

 creases the function and circulatory action of the heart without 

 irritating it ; on the other hand turpentine irritates the part to 

 which it is applied. If aromatic spirits of ammonia be given 

 internally the mucous membrane of the stomach will be irri- 

 tated and stimulated. If the dose is increased, it produces in- 

 creased functional activity through the increased local irritation 

 upon the mucous lining of the stomach. 



The secondary or constitutional disturbance of an irritant 



