Veterinary Andrology and Reproductive Techniques

PROSTATIC HYPERPLASIA

It is present in most dogs over 5 years of age that have not been castrated.

• The condition is probably due to an endocrine imbalance with an excess of testosterone being secreted which causes an enlargement and hyperplasia of the gland.

• The moderate to greatly enlarged gland may be smooth or nodular and may contain small cysts or occasionally excessively large cysts that extend forward into the abdominal cavity.
• The cyst walls may be calcified.
• In rare cases prostatic calculi have been reported.
• When cysts are not present the preputial discharge from an infected hyperplasia is usually purulent.
• When cysts are present the preputial discharge from an infected hyperplasia is watery-grey or bloody.
• The cystic fluid may be voided with the urine producing albuminuria.
• Dogs with marked hyperplasia are usually constipated.

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Rectal impaction and straining predispose to rectal dilation and the development of a perineal hernia.

• Rectal impaction and straining predispose to rectal dilation and the development of a perineal hernia.
• Rarely cystitis and hydronephrosis may develop.
• Usually little discomfort is shown by the dog with a hyperplastic prostate unless constipation or bladder strangulation occurs.
• Obstruction of the urethra does not occur in dogs as in man because of the bilobed nature of the gland in the dog in contrast to the trilobed structure of the gland in man.
• Digital examination of the prostate bimanually per rectum and by abdominal palpation may reveal a nodular or smooth, enlarged prostate.
• It is often helpful to exert pressure through the abdominal wall at the pelvic brim to push the prostate caudally so that it can be palpated.
• The consistency will vary with the nature of the hyperplasia from firm and fibrous, to soft, or even fluctuating if cysts are present.
• Normal prostate glands are 2.5 to 3 cm in diameter while hyperplastic glands may be twice as large or even larger if cysts are present.

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• Radiography may also be helpful in the diagnosis of prostatic enlargement.
• A perineal punch biopsy of the prostate gland is conclusive evidence of the nature of the enlargement.
• Rectal massage of the gland may give temporary relief by reducing the size of the cysts.
• Estrogenic therapy, such as injections of 0.5 to 1 mg of stilbestrol per pound of body weight daily and then gradually reducing the dose during the next few weeks, may give relief but continued dosing is required.
• Estrogens act by suppressing the pituitary gonadotropins and this causes an atrophy of the leydig cell and suppression of the testosterone production. the estrogens do not antagonize the androgens.

  The most satisfactory method of reducing the size of the prostrate is castration, as this removes the source of androgen causing hyperplasia. Within 2 to 3 weeks after castration the prostate gland begins to noticeably involute and by 6 to 8 weeks it is relatively small in size and atrophied.

• However castration does not reduce the large cysts or abscesses in infected glands or affect caliculi that may rarely be present. In complicated cases, surgery on the gland may be indicated.
• A chelating agent, sodium diethyldithio-carbamate is used for removing zinc which is in very high concentration in the prostate gland. This causes a probable cessation of much of the glandular enzymal activity and atrophy of the gland.

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