This has been seen almost exclusively in old dogs, among the domestic animals.
Causes. Age and good living, more particularly on highly albuminous food, may be adduced as the most prominent. Perhaps even more important are continued irritation in adjacent organs such as the rectum, bladder and urethra. It is the old, pampered dog that above all suffers from atonic, overloaded rectum, proctitis, piles, calculus, cystitis, and stricture, and the constant local pelvic congestion caused by one or other of these tends to a hyperplasia of the prostate. Again atheroma which is especially a disease of the aged is regarded as a cause of both cystitis and prostatic hypertrophy. Chronic inflammation in the prostate has been claimed as a factor, but contested on the ground that inflammation never increases normal growth though it may cause degeneration. The exudate of inflammation, tends, however, on its temporary arrest, to undergo organization, and such organization inclines to assume the structure which is normally built up by the adjacent trophic cells. The products of inflammation may, therefore, well contribute to hypertrophy, and above all to the increase of the simpler tissue represented by the fibrous framework of the gland. The congestion attendant on excessive venery has also been incriminated, and this too has been denied on the ground that the hypertrophy is not found in the young animals and men in which the generative ardor is greatest and most frequently aroused and gratified. Thompson’s idea is that the prostate, like the ovaries and womb, is especially prone to morbid growths and developments at the time when in advancing age, the normal generative functions are undergoing a rapid decline. The two conditions may well be recognized without considering them as mutually excluding each other as causative factors.
Lesions. The enlargement is usually general, but it may predominate in the right, left or median lobe, the latter as a rule exercising greater compression of the urethra so that this is often marked in the worst cases. The hyperplasia may feel firm and resistant or it may be more or less soft from sacs of muco-purulent fluid imprisoned by the obstruction of the outlet canals. On the surface and on section the general appearance of the gland is pale, bloodless and uniformly solid. This comes from the great hypertrophy of the fibro-muscular stroma which has in many cases compressed the parenchymatous or secreting structure so as to cause its atrophy. The presence of calculi (mainly phosphatic) in the follicles is not uncommon.
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.
Treatment. This has been considered as mainly palliative. Special care of the general health and above all of the diet which should be moderate, farinaceous and laxative, protection against cold and wet, the correcting of any coexisting trouble of the urinary or generative organs, and the removal from all sources of generative excitement are important elements. Occasional small doses of Epsom or Glauber salts in draught or enema obviate rectal hyperæmia. Ergot, potassium iodide internally, and iodine or mercurial ointment to the perineum have had little good effect. Möller claims to have secured improvement from the injection into the prostate at intervals of fourteen days, of a solution of two parts each of tincture of iodine and iodide of potassium, and sixty parts of distilled water. A small hypodermic syringe is used and the injection is made through the rectum directly into the substance of the prostate. Glass has adopted the recent surgical alternative of castration, with the result of marked relief from the active symptoms in a number of cases, but with a more rapid advance through emaciation and marasmus to death in three or four weeks in others. We would suggest a careful antiseptic castration in such cases, to obviate any added trouble from absorbed toxins or sepsis.
For the human subject, Lydston strongly advocates removal of the enlarged prostate by surgical means in strong, vigorous subjects, with healthy bladder and kidneys. The difficulty of such an operation in the dog is greatly enhanced by the relatively greater length of the pubio-ischiatic symphysis, and the lessened diameter of the pelvic cavity. Yet with the comparative immunity of the dog from suppuration, and the hopelessness of the case without such radical measure, and with the rigid application of an antiseptic technic, the operation would appear to be fully justified. It would be contra-indicated in all advanced cases, in which the prostate was the seat of active suppuration with discharge into the urethra, in cases complicated by urethritis, cystitis or nephritis, in cases in which there is marked prostration from sepsis or absorbed toxins, and generally in old, worn out and cachectic animals.
Short of this, in cases complicated by cystitis, antiseptics by the stomach and as injections into the bladder are desirable. Eucalyptol in doses of ten minims four times a day, or beta naphthol, guaiacol, or phenol have been used in man. As injections mercuric chloride 1:20,000; boric acid, saturated solution; or carbolic acid ·5:100 (Lydston) may be used warm several times a day.