INFECTIOUS DISEASES. 519 



which indicates the importance of running the hand daily over 

 the hoofs to detect any sudden elevation of temperature on their 

 surface. 



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 may simulate anthrax in the 

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

 membranes of the eyes, and a certain amount of swelling of the legs 

 and under surface of the belly. The diagnosis here can be ,made 

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

 variola, and scalma we have an intensely 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 ex- 

 cept in severe cases which have lasted for several days. In influenza 

 we have no evidence of the formation of pus on the mucous mem- 

 branes as in the other diseases, except sometimes in the conjunctivae. 



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 legs ; but in pneumonia we have the 

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

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

 eral days, while in influenza we have the history of characteristic 

 symptoms for several days before the rapid breathing and difficulty 

 of respiration indicate the appearance of the complication. Without 

 the history it is frequently difficult to diagnose a case of influenza of 

 several days' standing, complicated by pneumonia, from a case of 

 severe pneumonia of five or 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 

 influenza may aid in the diagnosis. 



Prognosis. — Influenza is a serious disease chiefly on account of its 

 numerous complications. Uncomplicated influenza is a compara- 

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

 In some outbreaks, however, complications of one kind or another 

 preponderate; in such instances the rate of mortality is much in- 

 creased. 



Alterations. — ^The chief alteration of influenza occurs in the diges- 

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

 mucous membrane, and especially of the Peyer's patches near the 

 ileocecal valve. The tissues throughout the body are found stained, 

 and of a more or less yellowish hue. There is always found a con- 

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

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

 the congested and discolored condition of the rest of the tissues. 



