The complication of infective cystitis is frequent, the congestion, redness, ecchymosis, maculation, puckering and thickening of the mucosa, the granular degeneration and desquamation of the epithelium, the exposure of a raw vascular surface, the discoloration of the urine by mucus, pus and blood, and the formation of ammonia and other products of decomposition, becoming marked phenomena. Vesical calculus is not uncommon, the slowness of the exit current of the urine retarded by the enlarged prostate, tending to prevent its impaction in the orifice and thus minimizing one of the most prominent symptoms. _Symptoms._ Among the earliest symptoms, is some modification in the act of micturition. Straining a few seconds before urine comes, retention, incontinence and dribbling, discharge in a small or weak stream, and sudden arrest of the flow and the last few drops may contain muco-pus showing abundance of spermatic crystals, on the addition of ammonia phosphate. Impaction of the rectum tends to occur sooner or later, the animal making little effort to unload the viscus, and the overdistended organ becoming more and more atonic, congested and catarrhal and reacting injuriously on the urinary organs. Incontinence may be especially marked during sleep, the sphincter being sufficiently controlled by volition during waking hours. Retention may be at first temporary from excitement and later more continuous by reason of the greater compression of the neck by the enlarged and indurated prostate. With the advance of the disease the urine shows abundance of triple phosphates, and becomes ammoniacal and fœtid. A dark or bloody color of the discharge and the presence of crystals suggest calculus. An accurate _diagnosis_ can only be had by rectal examination. The great enlargement of the prostate, in the absence of heat and tenderness is characteristic. Enlargement is usually uniform, though it may be concentrated on the right, left or central lobe. The passage of the catheter may be obstructed, but is not specially painful at the prostatic region as in prostatitis. From =vesical calculus= it is distinguished by the fixity of the swelling on the neck of the bladder as contrasted with the mobility of the stone inside that half-filled organ. From =stricture= it is differentiated by the fact that the obstruction offered to the catheter and the swelling of the prostate exactly correspond in position, that the stream is lessened in force rather than simply reduced in size, and that the history of the case shows no antecedent cause for stricture.