Symptoms. 187 



provement and repeated relapses, until finally the animal dies 

 from exhaustion, or remains broken-winded for the rest of 

 its life. Death may result however even earlier at the height 

 of the pneumonia, usually following paralysis of the heart. 

 Convalescence in this form of influenza takes a considerably 

 longer time, and as a rule extends over a period of more than 

 two weeks. 



The termination of the disease is naturally also influenced 

 by the existing hygienic conditions, and especially the continued 

 working of animals already ill will usually render the course 

 of the disease, which otherwise might have been only mild, an 

 unfavorable one. 



After the termination of the acute disease, chronic processes 

 sometimes develop as sequelaoea After a severe pneumonia, 

 and especially when the tissues in different parts have 

 become gangrenous, chronic granulating inflammatory proc- 

 esses, with shrinkage of the lung tissue, may develop. This 

 condition may also result in the formation of bronchiectasis, 

 while after an exudative pleuritis, adhesions of the pleural 

 layers may follow, as a result of which the animal may suffer 

 from dyspne. until its death. A frequent result of pleurisy 

 is the paralysis of the N. recurrens vagi, which causes roaring 

 in the animal. The acute catarrh of the intestines may develop 

 into a chronic form, which results in the gradual emaciation 

 of the animal. Other after affects that may occur are paralysis 

 of the hind parts, shortening and even necrosis of some of the 

 tendons, chronic inflammation of the joints, exostoses, hemo- 

 globinemia, and as a result of the inflammation of the eye, 

 amaurosis. Finally, horses recovering from influenza may later 

 become affected with purpura hemorrhagica, and the internal 

 inflammation of the eye may also develop only two to three 

 weeks after the passing of the disease (Hell). 



The character of the disease varies greatly in the different 

 outbreaks. While in some periods the course of the disease is 

 very mild, so that the great majority of the animals are only 

 slightly affected with the catarrhal s^^uptoms, and while also 

 the infrequent pneumonia almost invariably terminates in re- 

 covery, there are outbreaks in which the disease is of a re- 

 markably malignant character. This form is characterized 

 especially by frequent hemorrhages, as well as by pneumonias 

 which frequently assume gangrenous forms. The character of 

 the disease may also change in one and the same outbreak; 

 thus in some instances it may occur that at the beginning of 

 the outbreak only cases of the catarrhal form of influenza 

 are observed, while later the pleuro-pneumonic form becomes 

 more frequent, and towards the termination of the epidemic 

 the affections return again to the milder form. 



Diagnosis. The catarrhal form of influenza may be easily 

 mistaken for catarrhal manifestations of the mucous mem- 



