500 BUREAU OF ANIMAL INDUSTRY. 



same stable T^'C^c affected. Brick walls, old woodwork, and the dirt 

 which is too frequently left about the feed boxes of a horse stall will 

 all hold the contagion for some days, if not weeks, and communicate 

 it to susceptible animals when placed in the same locality. A four- 

 year-old colt, belonging to the writer, stood at the open door of a stable 

 where two cases of influenza had developed the day before, fully 40 

 feet from the stall, for about ten minutes on two successive mornings, 

 and in six da3's developed the disease. On the morning when the 

 trouble in the colt was recognized it stood in an infirmary with a dozen 

 horses being treated for various diseases, but was immediately isolated; 

 within one week two-thirds of the other horses had contracted the 

 disease. 



Symj)toms. — After the exposure of a susceptible horse to infection a 

 period of incubation of from four to seven da3^s elapses, during which 

 the animal seems in perfect health, before any S3^mptom is visible. 

 When the symptoms of influenza develop they nvAj be intense or they 

 may be so moderate as to occasion but little alarm, but the latter con- 

 dition frequentl}^ exposes the animal to use and to the danger of the 

 exciting causes of complications which would not have happened had 

 the animal been left quietly in its stall in place of being worked or 

 driven out to show to prospective purchasers. The disease mav run a 

 simple course as a specific fever, with alterations only of the blood, 

 or it ma}' become at any period complicated b}' local inflammatory'- 

 troubles, the gravity of which is augmented by developing in an 

 animal with an impoverished blood and already irritated and rapid 

 circulation and defective nutritive and reparative functions. 



The first symptoms are those of a rapidly developing fever, which 

 becomes intense within a very short period. The animal becomes 

 dejected and inattentive to surrounding ol)jccts; stands with its head 

 down, and not back on the halter as in serious lung diseases. It has 

 chills of the flanks, the muscles of the croup, and the muscles of the 

 shoulders, or of the entire body, lasting from fifteen to thirt}' minutes, 

 and frequently a grinding of the teeth which warns one that a severe 

 attack may be expected. The hairs become dr}^ and rough and stand 

 on end. The body temperature increases to 104°, 104.5°, and 105° F., 

 or even in severe cases to 107° F., within the first twelve or eighteen 

 hours. The horse becomes stupid, stands inunobile with its head hang- 

 ing, the ears listless, and it pays but little attention to the surrounding 

 attendants or the crack of a whip. The stupor becomes rapidly more 

 marked, the eyes become puffy and swollen with excessive lachryma- 

 tion, so that the tears run from the internal canthus of the e3"e over the 

 cheeks and may blister the skin in its course. The respiration becomes 

 accelerated to twent3'-five or thirty in a minute, and the pulse is quick- 

 ened to seventy, eight3'', or even one hundred, moderate in volume and 

 in force. There is great depression of muscular force; the animal 



