142 VETERINAET STATE BOARD 



the body and changes are produced there, the later formed lesions 

 are secondary. For example, from an abscess on the leg (primary 

 lesion) infection may be carried to the lungs, liver, etc., and produce 

 abscesses in these parts (secondary lesions). 



State what value you would give to each of the following agents in 

 the development of an infectious disease: microbes, chill, 

 electric tension, imperfect ventilation, impure water, de- 

 cayed or indigestible foods, emanations from sewers, cess- 

 pools or heaps of manure, impaired health or vigor from 

 previous illness, fatigue, overwork, damp soils, exposure 

 to hot summer sun. 

 The first named agent, microbes, and it only, can produce the 

 disease alone. The other agents can only act as accessory factors in 

 lessening the resisting powers but none of them alone, or together, 

 can produce an infectious disease without the causative factor, the 

 microbe. 



What lesions and conditions would indicate that an animal had been 

 killed by lightning? 



Blood is dark and imcoagulated, the muscles dark brownish-red, 

 the endocardium stained by the altered blood and the heart muscle 

 shows hemorrhagic infarcts in death by lightning. The tissues may 

 be lacerated, showing hemorrhages. Branching, tree-like lines of 

 singeing along the course of the current. Rapid decomposition with 

 slight rigor mortis. 



Conditions aiding diagnosis are: fact of lightning storm; ani- 

 mal being found under a tree which shows the effects of the current. 



What is meant by auto-intoxication ? 



Auto-intoxication is a poisoning of the organism by substances 

 which arise in the body itself through its own activity, that is, it 

 is a self-poisoning. The poisoning is the residt of the absorption 

 of the waste products of metabolism or of the products of decom- 

 position within the intestines. 



Define metastasis. Give examples. 



Metastasis is the transportation through the blood- or lymph- 

 stream of a disease-producing agent and the production of disease 

 at the point of deposit of such agent, e.g., living cells of tumors may 

 be carried to distant parts and produce daughter tumors at the 

 site of lodgement. Vegetable or animal parasites are carried in the 

 blood-stream from one part to another, producing disease at their 

 point of lodgement. The movement of emboli in the blood-vessels 

 is an example of metastasis. 



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