INFECTIOI'S DISEASES. 523 



Old, cold, ilainp. foul, iiiicleaii. ami liadly diainod and \ eiitiliited 

 stables allow rapid dissemination of the disea.se to other horses in the 

 same stable and aet as rich reseivoiis for |>reservin<; the contaj^ion, 

 whiih may be letaini'd for o\er a year. 



The virus is but moderately volatile, and in a stable seems rather 

 to follow the lines of the walls an«l iri-e<i;ular courses than the ilirect 

 currents of air and the tract^s of ventilation. Prof. Dieckerhoff 

 found that the conta<;ion of influen/a was leadily (lillusii)le throu<xh- 

 out an entire stable anil through any oi)ening to other buildings, but 

 he also fouiul that the contagion of infectious pneumonia is not trans- 

 mi.ssible tit any great distance, nor is it very dirt'usil)le in the atmos- 

 phere. A brick wall 8 feet in height served, in one instance, to pre- 

 vent the infection of other animals placed on the opposite side from 

 a horse ill with the disease, while others placed on the same side 

 ami separated from the focus of contagion only by open bai^s in the 

 stall were infected and developed the disease in its typical form. 



Symptotns. — The .symptoms differ .slightly from those of a frank, 

 fibrinous pneumonia, but not so much by the introduction of new 

 symptoms as by the want of or absence of the distinct evidences of 

 local lesions which are found in the latter disease. All the pneu- 

 monias throughout the whole course of the trouble are less marked 

 and less clearly' defined. 



The symptoms may develop slowly or rapidly. If slowly, there is 

 fever and the animal gives a rare cough which resembles that of a 

 heavy horse affected with a slight chronic bronchitis; it becomes 

 somewhat dejected and dull, at times somnolent, and has a dimin- 

 ished ai)petite. This condition lasts for several days, or the disease 

 may begin with high fever, and the symi)toms described below are 

 severe and delevop in rapid sequence. The respirati(m increases to 

 24, 30, or 3G to the minute, and a small, lunning, soft jmlse attains a 

 rhythm of 50, 70, or even more beats in the si.xty secounds. The heail, 

 however, contrary to the debilitated condition of the pulse, is found 

 beating violently and tumultuously, as it does in anthrax and septic 

 intoxication. The mucous membranes of the eyes and juouth and of 

 the genital organs are found somewhat edematous, and they rapidly 

 assume a dirty, saffion color, at times apjiroaching an ocher, but dis- 

 tinguishable fi-om the similai- coloiation in influenza by the want of 

 the luster belonging to the latter and by the muddy, dull tint, which 

 is characteri.stic throughout the disease. 



Suddenly, without the preliminary rales which precede grave 

 lesions of the lungs in other diseases, the blowing nnirmur of pneu- 

 monia is heard f)ver a variable area of the chest, usually, however, 

 nmch more distinctly over the tiachea at the base of the neck and 

 directly behind the shoulder on each side of the chest. In .some cases 

 the evidence of lung lesion can be detected only over the trachea. 



