180 Influenza of Horses. 



the preexisting catarrhal manifestations were really indica- 

 tions of infection with influenza. 



According to Siedamgrotzky the time of incubation in influenza is from 4 to 

 5 days, while Dieckerhoflf claims that the first manifestations appear in from 12 to 

 24 hours. On the other hand, even 14 days may in exceptional cases elapse before 

 the onset of the disease. In infections which are transmitted by coitus the disease 

 usually develops in from 6 to 9 days (Clark, Jensen, Grimme). 



The disease commences almost invariably with marked de- 

 pression, dullness of the sensibility, and capricious appetite. 

 The animals stand with eyes half closed, ears drooped, support- 

 ing the head to the crib or the strap of the halter, sometimes 

 standing in the stall, apathetic and in abnormal positions. 

 They take the food offered them with hesitation, masticate it 

 slowly, and with frequent interruptions. They frequently do 

 not swallow the bolus, but it lies in the mouth on the outside 

 of the molars apparently forgotten. If urged to move they 

 walk lazily and with some difficulty; frequently the gait is 

 staggering. 



The body temperature is first elevated, and reaches on the 

 first day of the affection 40 to 40.5° C. At this point the temper- 

 ature remains for two or three days with only slight variations, 

 whereupon in the catarrhal form, after one to two days more 

 it drops rapidly to normal (Fig. 35 on page 181). 



In the case of pure or predominating pneumonia the tem- 

 perature continues to remain high, with slight variations, and 

 returns to normal only after the regeneration of the changes 

 in the lungs (Fig. 36 on page 183). In severe cases the fever 

 persists continuously or remittently until death. In slowly 

 progressing cases however the fever is interrupted periodically 

 by afebrile intervals (Fig. 37 on page 186). During the period 

 of high fever the heat over the surface of the body is unevenly 

 distrilDuted, the coat is rough; muscular trembling may be also 

 observed in some parts of the body. The skin sometimes mani- 

 fests nodular eruptions or urticara. The heart's action is from 

 the beginning more or less excited, in severe cases it is greatly 

 accelerated and weak, as a result of the developing parenchy- 

 matous degeneration of the heart muscle. The pulse is usually 

 from 50 to 60 per minute ; in severe cases, however, the number 

 may increase to from 80 to 100, with throbbing heart and small, 

 wiry pulse. 



Special Symptoms of the Catarrhal Form of Influenza. 

 In this form of the disease catarrhal manifestations of the 

 mucous membranes develop in association with the above de- 

 scribed febrile symptoms. 



In the eyes the conjunctivae appear reddened (mahogany 

 or brick red), frequently with a yellowish tint, the submucous 

 connective tissue containing a serous infiltration. There is 

 always photophobia as well as lachrymation present. The 

 eyelids swell, and the opening of the eye is thereby narrowed. 



