INFECTIOUS DISKASKS. 513 



stable in -which two cases of influenza had hiokon out the (lav before: 

 ill six (lays the coU developed the disease. On the nioi-ning when the 

 trouble in the colt was reco^Miized it st(M)d in an infirniarv with a 

 dozen horses that were l)eiii<j: treated for \arious diseases, l)nt was 

 innnediately isohded: within <tiie week two-thirds of tho other lioi-ses 

 had contracted the disease. 



Sijniptoms. — After the exposure of a susceptible hor.se to infection 

 a period of incubation of from four to .seven days ehipses. duiinp 

 which the animal seems in i)erfect health, before any symptom is 

 visible. AVhen the symptoms of influenza develop they may be in- 

 tense, or so moderate as to occasion but little alarm, but the latter 

 condition fre(iuently exposes the animal to use and to the dan<rer of 

 the exciting causes of complications which would not have hai)pened 

 had it l)een left (piietly in its stall in j)la(e of being woi-ked or dri\ en 

 out to show to prospective purchasers. The disea.se may run a 

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

 or at any period it may become complicated by local inflammatory 

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

 animal with an impoverished blcK)d, an already irritated, rapid cir- 

 culation, and defective nutritive and rei)arative functions. 



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

 l)ecomes intense within a very short period. The animal becomes 

 dejected and inattentive to surrounding objects; .stands with its head 

 down, and not back on the halter as in serious lung di.seases. In 

 the flanks, the nm.scles of the croup and of the shoulders, or of 

 the entire body it has chills lasting from 15 to 30 minutes, and 

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

 attack may be expected. The hairs Ix'come dry and rough and stand 

 on end. The body t<?mperature increases to 104°, 104.;")°, and 105° F., 

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

 houi-s. The horse becomes stupi(l, .stands immoljile with its head 

 hanging, the ears li.stless, and it pays but little attention to the sur- 

 rounding attendants or the crack of a whip. The .stupor becom(\s 

 rapidly more marked, the eyes become pufl'y and swollen with ex- 

 cessive lacrimation. so that the tears run from tlie internal canthus 

 of the eye over the cheeks and may blister the skin in their course. 

 The respiration becomes accelerated to 'lU or .'{() in a minute, and the 

 l)ulse is (|uickened to 70, 80, or even 100, moderate in volume and in 

 force. There is great depression of muscular force: the animal stands 

 limp, as if excessively fatigued. There is diminution, or in some 

 cases total lo.ss, of sensibility of the skin, so that it may he pricked 

 or handled withotit atti-acting the attenticm of the animal. On move- 

 ment, the horse staggers an<l shows a want of coordination of all the 

 muscles of its limbs. The senses of hearing, sight, and taste are 

 36444°— Iti 33 



