506 BUREAU OF AI7IMAL INDUSTKY. 



The diagnosis of brain trouble is based upon the excessive violence 

 which occurs in the course of the disease, for during the intervening 

 period or coma there is no means of determining that it is due to this 

 complication. Severe cases of influenza maj' simulate anthrax in the 

 horse. Jn both we have stupor, the intense coloration of the mucous 

 membranes of the e3-es, and a certain amount of swelling of the'legs 

 and under surface of the bellv. The diagnosis here can be made onlj- 

 by microscopic examination of the blood. In strangles, equine variola, 

 and scalma we have an intense red, rosy coloration of the mucous 

 membranes, full, tense pulse, and, although in these diseases we may 

 have depression, we do not have the stupor and coma except in severe 

 cases which have lasted for some da3's. In influenza we have no evi- 

 dence of the formation of pus on the mucous membranes as in the 

 other diseases, except sometimes in the conjunctivae of the eyes. 



In severe pneumonia (lung fever) we may find profound coma, dark 

 yellowish coloration of the mucous membranes, and swelling of the 

 under surface of the belly and logs; but in pneumonia we have the 

 history of the difliculty of breathing and an acute fever of a sthenic 

 type from the outset, and the other symptoms do not occur for several 

 days; while in influenza we have the liistor}" of characteristic svmp- 

 toms for several days l>efore the rapid breathing and difficulty of res- 

 piration indicate the appearance of the complication. Without the 

 history it is frequently difficult to diagnose a case of influenza of sev- 

 eral days' standing complicated by pneumonia, from a case of severe 

 pneumonia of five to six days' standing, but from a prognostic point 

 of view it is immaterial, as the treatment of both are identical. The 

 fact that other horses in the same stable or neighborhood have influ- 

 enza may aid in the diagnosis. 



Prognosis. — Influenza is a serious disease chiefl}' on account of its 

 numerous complications. Uncomplicated influenza is a comparatively 

 simple malady, and is fatal in but 1 to 5 per cent of all cases. In 

 some outbreaks, how^ever, complications of one kind or another pre- 

 ponderate; in such instances the rate of mortality is much increased. 



Alteratlo7is. — The chief alteration of influenza occurs in the digest- 

 ive tract, and consists in hyperemia, infiltration, and swelling of the 

 mucous membrane, and especially of the Pej-ers' patches near the ileo- 

 cecal A^alve. The tissues throughout the body are found stained, and 

 of a more or less yellowish hue. There is always found a congested 

 condition of all the organs, muscles, and interstitial tissues of the 

 body. The coverings of the brain and spinal cord partake in the con- 

 gested and discolored condition of the rest of the tissues. 



Other alterations are dependent entirel}^ upon the complications. 

 If the lungs have been affected, we find effusions identical in their 

 intimate nature with fhose of simple pneumonia, but they differ some- 

 what in their general appearance in not being so circumscribed in 



