Specific Contagious Diseases. 97 



frequently of other organs. It has prevailed at intervals 

 over different parts of the world in man, horses, dogs, and 

 even cats. 



Causes. Nothing can be definitely stated as to the pri- 

 mary cause of its development, as all peculiar conditions of 

 soil, volcanic action, atmospheric electricity, aerial moisture 

 or dryness, density or levity, season, temperature, winds, 

 calms, ozone, and antozone fail to account for its appearance. 

 The great American epizootic of 1872 was preceded and ac- 

 companied in Michigan by an excess of ozone, but tlie excess 

 did not determine its appearance in other States, which it 

 invaded by a gradual progress and with a rapidity propor- 

 tional to the celerity, of communication. Again, insular and 

 sequestrated places escaped, as Prince Edward's Island, 

 (frozen out), Vancouver's Island (quarantined). Key West, 

 Hayti, St. Domingo, Jamaica, La Paz, by the non-importa- 

 tion of horses (Cuba suffered through imported American 

 horses). It stopped at Panama, wJiere there is no horse 

 traffic, owing to the state of the country. (See the autlior's 

 report to Government, and report of New York Board of 

 Ilealtli.) 



Symptoms. The disease comes on suddenly with extreme 

 weakness and stupor. There is often pendant head, half- 

 closed, lustreless eyes, great disinclination to move, with 

 swaying gait, and cracking joints. Appetite is lost, mouth 

 hot, clammy, bowels costive, urine scanty and high-colored, 

 pulse accelerated and weak (sometimes hard), a cough, deep, 

 painful, and racking comes on, crepitation or harsh blowing 

 sounds are heard in the chest, and the membrane of the nose 

 assumes a bright pink or dull leaden line. The ears aud 

 limbs are alternately cold and hot, the hair I'ough, the skin 

 tender and frequently trembling. 



Soon the nose dischai-ges a white, yellowish, or greenish 

 matter, and the animal may recover, or an increasingly heavy 

 breathing, depth and painfulness of cough, and changed or 



