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 conjunctive. 
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. 
