“Briefly, the symptoms, as stated in a recent publication of the United States Department of Agriculture, are sudden onset; fever in some cases preceded by chill; great physical prostration and depression of nervous force; sometimes injected mucous membranes, especially those of the eye, and loss of appetite. In uncomplicated cases the fever abates after about a week and there is a general restoration to health. Pneumonia is one of the frequent complications and is always serious. The death rate varies between two and seven per cent. The most usual form is the catarrhal type. The attack may last only two or three days; in other cases the course may extend to two weeks, in which event it takes the animal a long time to get well. Horses which have passed through this form of disease may be considered to have recovered two weeks after the disappearance of the fever. “The diagnosis of influenza depends as much upon its epidemiological aspects as upon the symptoms. Law bases it on the suddenness of the attack, its epizootic character, the numbers attacked in rapid succession and over a large area as compared with ordinary contagious pneumonia, the sudden and extreme prostration, the mildness of the average case, the congestion of the upper air passages, the watering and discoloration of the eyes, and the history of the case. Points of interest in the history are the arrival of the infected horses within a few days from an infected place, or coming through such a place, or the attacking of new arrivals in a previously infected stable, or the known advance of the disease toward the place where the patients are located.” Soper found that the progress of the epidemic of 1872–73 among the horses in this country was as generalized, but much slower than the progress of the recent pandemic among human beings, the rapidity of progress corresponding with the rapidity of the transport of the horses at that time. Just as we have found in the case of influenza so also at that time the spread only followed lines of communication and actual contact between horses. It is highly interesting that attempts to transfer the disease from horse to horse experimentally met with the same degree of failure that was experienced in similar attempts to transfer influenza experimentally from man to man. In fact Lieut. Col. Watkins Pitchford of the British Army Veterinary Corps in a report in July, 1917, stated that it was impossible to produce infection experimentally. Nose bags were kept upon horses with profuse nasal discharges and high temperature, and these nose bags were then used to contain the food of other horses without infection taking place.