_Initial pathognomonic symptoms._ Certain prominent and striking symptoms are so constantly present in the earlier part of the disease that they may be held as virtually diagnostic. These are the _suddenness of attack_, the _anorexia_, the _profound early prostration and weakness_, the _high temperature_, _the swelling and watering of the eyes_, and the specially _brownish red coloration of the conjunctiva and other visible mucosæ_. The attack may come on with almost lightning rapidity. The animal which yesterday, or it may be but an hour or two ago, appeared to be in the most vigorous health and spirits, is found with pendant head, resting perhaps on the manger, ears drooping, eyelids swollen and half closed, epiphora, conjunctiva of a brownish red or violet, lips loose and drooping, and one or two legs partially flexed, while the body is balanced on the others. The patient is indisposed to move, and when compelled to walk may sway and stagger from nervous and muscular weakness. The arched back, cracking limbs, and their stiff, rigid movement further indicate the suffering in muscles or joints or both. Appetite is greatly impaired or lost, thirst marked, and hyperthermia 102° to 105° or upward. Sneezing, cough or symptoms of some other special localization may be present, but the above occurring in a number of horses at once, without appreciable climatic cause, when one or two new horses have been very recently acquired, or when influenza has been prevailing in the vicinity or in a neighboring place, will usually stamp the nature of the attack. Cadeac considers the sudden attack, high fever, and profound nervous prostration and stupor as the manifestations of the uncomplicated disease, while the localizations in the lungs, bronchia, pleura, liver, bowels, etc., are indications of complications by germs of other diseases, which find the debilitated influenza system especially open to attack. The _fever_ which always sets in early may be little above the normal in mild cases, and may reach 107° or 108° F. in the more severe ones. It may last thus for five or six days and then rather suddenly descend to near the normal. In other cases it descends a little daily, the lowest temperature for the day being seen in the morning. Shivering is often nonexistent or passes unperceived. The _pulse_ does not usually encrease in ratio with the temperature. It may be at first only 40 or 50 per minute, though later, and especially with extensive disease of important organs, it may reach 60, 70, 80 or even 100. It usually lacks in firmness and force, even when the heart beats forcibly, being soft, somewhat compressible, and often irregular in successive beats, the weakest corresponding to the last part of the inspiratory act, or when the lungs are full and the heart compressed. The _heart_ impulse behind the left elbow is usually forcible and may show variation in rhythm or even intermissions.