Prostate Gland
This almost spherical gland is located on the neck of the urinary bladder of male dogs. It is 1.5-2.5 cm in size, varying with the size of the dog. There are two components. The body of the prostate is a discrete bulbous gland lying dorsally on the neck of the bladder.
The disseminate part of the prostate lies along the urethra. Both components have many secretory ducts. The size of the prostate varies in the domestic species, that of the dog being the relatively largest and that of the ox relatively the smallest.17.2.1 Species variations
Horse (Figure 15.1): Only the body of the prostate is present, and in this species it is distinctly bilobed with a connecting isthmus. It is compact with multiple ducts. It lies across the neck of the bladder at the beginning of the pelvic urethra and covers the terminal sections of the deferent ducts of the vesicular glands. It comprises two lobes connected by an isthmus. The 16-20 ducts open independently on either side of the colliculus seminalis. The prostate is mainly retroperitoneal and can be palpated per rectum.
Ox (Figure 15.4): Both a body and a disseminate part are present. The body is small and slightly lobulated. The disseminate part is larger than the body but invisible superficially because it is covered by the urethral muscle. It opens into the pelvic urethra by a series of dorsal ducts.
Sheep: At a similar location to that of the ox, but only the disseminate part is present, and this is only present on the dorsal and lateral aspects of the urethra.
Pig (Figure 15.7): Both parts are present and resemble that of the ox, except that it is usually hidden by the large vesicular gland. The body of the prostate is small and irregularly shaped. The disseminate part lies within the wall of the pelvic urethra and discharges its secretion into the urethra through many openings.
Dog and Cat (Figures 15.9 and 15.11): Relatively large, comprising two hump-like lobes, and more prominent than in the other species. It surrounds the urethra and the neck of the bladder and is easily palpated per rectum in the dog owing to its large size in this species. Pathological enlargement may occur when both the rectum and the urethra may become obstructed. In these species the prostate gland produces the bulk of the seminal fluid. The two deferent ducts lie within the prostate and join the urethra within the gland. Prostatic secretion is promoted by the hypogastric nerve and up at a rate of up to 2 ml per hour.
Prostatic hyperplasia and neoplasia are common in older dogs. Inflammatory disease and prostatic abscesses occur not infrequently.
17.3