_Causes._ As in stomatitis the starting point of pharyngitis is usually in a local injury or a systemic condition which lowers the vitality of the pharyngeal mucous membrane. It may come in all animals from the hot air of burning buildings, from acrid gases inhaled, food, drink or medicines given at too high a temperature, from caustic alkalies, acids or salts, from physiological irritants like croton, euphorbium, cantharides, from barley and other spikes entangled in the follicles, from drinking freely of iced water. In _solipedes_ there are the injuries caused by giving boluses on pointed sticks, and the wounds caused by tooth files in careless hands, and by coarse fibrous fodder, which has been swallowed without due mastication. In _cattle_ injury comes from foreign bodies impacted, from the rough use of probang, rope or whip and even of the hands in relieving choking. _Swine_ have the part scratched and injured by rough or pointed objects which they bolt carelessly with the food. _Dogs_ and especially puppies are often hurt by solid and irritant bodies that they play with, and swallow accidentally or wantonly. They also suffer at times from the pressure of a tight or badly adjusted collar. The system is debilitated and rendered more susceptible by chills consequent on exposure to cold blasts, or draughts, or rain or snow, when heated and exhausted, by cold damp beds, by pre-existing disease, by underfeeding and by overwork. In the larger animals this may come from the excessive ingestion of iced water, while in dogs the plunging in rivers, ponds or lakes may chill. The weakness of _early age_ and _old age_ have a perceptible predisposing influence especially in solipeds and carnivora. Finally as in other catarrhal inflammations the local action of disease germs on the mucous membrane must ever be borne in mind. These may be the germs of specific diseases localized in the pharynx;—in =Solipeds= the streptococcus of strangles, the bacillus of glanders, the diplococcus (streptococcus) of contagious pneumonia, the germ of influenza, and actinomyces;—in =Cattle= the bacillus tuberculosis, the bacillus of anthrax, actinomyces, the germs of aphthous fever and of pseudomembranous angina; in _dogs_ canine madness and distemper;—in birds the bacillus of pseudomembranous pharyngitis. In addition to such specific germs the micrococci, streptococci and bacilli which are normally present and harmless in the mouth and pharynx, enter, colonize and irritate the debilitated tissues in case of trauma, inflammation or constitutional disorder and serve to perpetuate and aggravate the affection.