_Causes._ The most common causes are mechanical injury of the Schneiderian membrane, violent congestion of this membrane during extraordinary excitement or exertions, as in coughing, in a closely contested race, in a trying hunt, in drawing heavy loads, especially if uphill and with a tight collar. It may coincide with congestion of the brain acting to some extent as a vicarious discharge, or with the formation of new structures as polypus, or cancer, in which, from the looseness and friability of their texture, the vessels readily give way. The softened membrane is equally liable to laceration or rupture during the progress of inflammation and particularly when fibrinous (croupous) exudations are being detached. In all these cases animals of a strong, vigorous constitution and with a full or plethoric habit are most liable to be attacked. Various congestions of the mucosa in diseases of the heart or lungs are additional causes. Disease or injury of the cervical branch of the sympathetic nerve, and varicosity of the pituitary venous plexus must be accepted as occasional causes. Epistaxis is also met with in states of general weakness and with deteriorated blood, as in anæmia, in the course of various fevers and in those hemorrhagic constitutions in which the altered blood appears to find an easy passage through the debilitated or ruptured coats of the bloodvessels. Thus it is seen in the so-called _purpura hemorrhagica_ in the horse, in _small-pox_ in sheep, in anthrax, and in _swine plague_ and hog cholera. _Hering_ records the case of a number of pigs suffering from a scorbutic affection and which bled profusely from the nose. In bleeders (hæmophilia) and in leucocythæmia it is liable to appear. The ulcerations of the mucous membrane occurring in _glanders_ and _chronic catarrh_ have proved exciting causes of the hemorrhage. Lastly the intense heats of summer and prolonged exposure to the direct rays of the sun induce a general relaxation and a determination of blood to the surface which rouses to activity the latent tendency. _Symptoms._ The bleeding, usually from one nostril only, falls in a succession of drops, (rarely in a stream), collects in clots around the nostril, and bespatters surrounding objects as it is expelled forcibly in sneezing. It is usually of a bright crimson hue or, in fevers or poisoned conditions of the blood, of a dark or blackish color. It is distinguished from pulmonary hemorrhage by the absence of cough and of a frothy condition, and from bleeding from the stomach by the absence of the blackened clots and acid odor which indicate the presence of the gastric juice. It is usually to be further distinguished from these in all animals, save solipedes, by the absence of blood in the mouth.