Chapter 113 - Prostate

Question 1

What is the normal size of the prostate?
What breed can have a healthy larger prostate?

Answer 1

• 0.64-0.96g/kg - higher ratios almost always mean changes are there
• Scottish Terriers

Question 2

Is the prostate peritoneal or retroperitoneal?

How does it move around with age?

Answer 2

Both! Its ventral aspect is retroperitoneal
It starts out abdominal -> urachal vestige breaks down at 2mo and it moves pelvic -> puberty starts an abdominal movement / half abdominal by 4 yr and moves to be fully abdominal by 10 yr of age

Question 3

What nervous input increases glandular secretion?

Answer 3

Parasympathetic supply from the pelvic nerve

Question 4

What are the 2 forms of acinar dilation are seen within the mature prostate? When do signs of activity appear?

Answer 4

• Simple dilatation: Many dilated acini with or without luminal eosinophilic secretions which no not compress adjacent acini
• Focal glandular ectasia: Focal dilatation of a few acini with eosinophilic content and compression of the adjacent prostatic parenchyma

Start around 4 months of age

Question 5

List the functions of the prostatic secretions:

Answer 5

• Promote spermatozoa motility and viability
• Increase uterine perfusion
• Modulate neutrophil-induced inhibition of spermatazoa attachment to uterine epithelium

Question 6

What hormone is relaeased from the prostate gland during ejaculation?

Answer 6

Large amounts of prostaglandin E2

Question 7

What substances are found within prostatic secretion? What is it’s pH?

Answer 7

• High concentration of zinc and zinc-binding proteins
• Acid phosphatase (also produced by epididymis)
• Canine prostate-specific esterase (90% total protein)

pH 6.1-6.5

Question 8

List anatomical differences of the feline prostate

Answer 8

• Only partially encircles the urethra (dorsolaterally)
• Can have some prostatic tissue disseminated within the urethral wall caudal to the prostate

Question 9

In the dog, where is the prostate located relative to the urinary bladder and urethra?

Answer 9

It lies immediately caudal to the bladder and completely encircles the proximal urethra as a bilobed gland.

Question 10

What is the only accessory sex gland in the male dog?

Answer 10

The prostate gland.

Question 11

What gross feature distinguishes the canine prostate externally, and where is the urethra positioned within the gland?

Answer 11

It is bilobed with dorsal and ventral midline sulci; the urethra is positioned closer to the dorsal surface of the gland.

Question 12

Which structures perforate the craniodorsal surfaces of the canine prostate to enter and open into the urethra near the colliculus seminalis?

Answer 12

The vasa deferentia enter bilaterally and open into the urethra via paired slits on each side of the colliculus seminalis.

Question 13

How does the craniocaudal position of the canine prostate change from birth through adulthood, and what developmental event is associated with early positional change?

Answer 13

It is abdominal early and becomes pelvic when the urachal vestige breaks down at ~2 months; with puberty and aging it enlarges and migrates cranially to become increasingly abdominal, often entirely abdominal later in life.

Question 14

What anatomic relationship makes the prostate clinically accessible on rectal exam, and what separates it from the rectum?

Answer 14

It lies dorsal to the pubic symphysis and ventral to the rectum; it is separated from the rectum by peritoneal folds filling the rectogenital space (with a fibrous band on the caudal dorsal third).

Question 15

What is the peritoneal covering pattern of the prostate and what is the key surgical implication?

Answer 15

Its dorsal surface has peritoneal covering, but the ventral aspect is retroperitoneal, influencing dissection planes and spread of fluid/hemorrhage.

Question 16

In some chondrodystrophoid dogs, how may prostate position differ from typical dogs?

Answer 16

The prostate may be intraabdominal from birth.

Question 17

What is the embryologic origin of the canine prostate gland and from what epithelium does it arise?

Answer 17

It is endodermal in origin and arises from pelvic urethral epithelium (urogenital sinus derivative).

Question 18

At approximately what gestational time do prostatic tubules first appear in the dog, and what do they look like histologically?

Answer 18

Around the sixth week of gestation, as solid epithelial projections from the urethra growing into surrounding mesenchyme.

Question 19

What tissue gives rise to the prostate stroma and smooth muscle, and what is a common trap about its source?

Answer 19

Surrounding mesenchyme differentiates into stroma and smooth muscle; much smooth muscle originates from the prostatic urethra (pelvic urogenital sinus).

Question 20

Why is the adult canine prostate described as a composite gland, and what tissues contribute to this composite?

Answer 20

It contains mesenchymal, urethral, and Wolffian duct tissues with glandular and nonglandular components within a common capsule.

Question 21

From which vessels do prostatic arteries most commonly arise in dogs, and at what sacral level is their origin often described?

Answer 21

They commonly branch from the internal pudendal vessels (or occasionally from umbilical arteries) at approximately S2–S3.

Question 22

What major collateral/anastomotic concept is a common Phase I ‘trap’ when considering prostatic hemorrhage control?

Answer 22

There are many anastomoses between prostatic arteries and urethral, cranial rectal, and caudal rectal arteries, so collateral flow can persist despite single-vessel ligation.

Question 23

How do prostatic arteries distribute across the gland before entering parenchyma?

Answer 23

They divide into cranial, middle, and caudal branches, distribute across dorsolateral surfaces, become subcapsular arteries, and then supply glandular tissue.

Question 24

What are the described vascular zones of the prostate?

Answer 24

Capsular, parenchymal, and urethral zones.

Question 25

What supplies the cavernous tissue immediately surrounding the prostatic urethra (key surgical trap)?

Answer 25

The artery of the bulb of the penis supplies cavernous tissue around the prostatic urethra.

Question 26

Where does venous drainage from the prostate primarily go?

Answer 26

Via prostatic and urethral veins into the internal iliac vein.

Question 27

To which lymph nodes does the prostate drain?

Answer 27

Medial iliac and hypogastric lymph nodes.

Question 28

Which two nerves provide autonomic innervation to the canine prostate via the pelvic plexus?

Answer 28

The hypogastric and pelvic nerves (forming the pelvic plexus/prostatic plexus).

Question 29

Which postganglionic fiber type is most directly linked to fluid excretion by secretory epithelium, and which nerve is it associated with?

Answer 29

Cholinergic postganglionic fibers associated with the hypogastric (sympathetic) nerve control epithelial fluid excretion.

Question 30

Which postganglionic fiber type regulates smooth muscle contractions responsible for dynamic prostatic fluid movement, and which nerve is it associated with?

Answer 30

Adrenergic postganglionic fibers from the hypogastric nerve regulate prostatic smooth muscle contractions.

Question 31

What is the reported effect of parasympathetic input from the pelvic nerve on the prostate?

Answer 31

It increases the rate of glandular secretion.

Question 32

What type of innervation is rich within prostatic stromal tissue and what does it regulate?

Answer 32

Rich noradrenergic innervation regulates prostatic smooth muscle tone.

Question 33

What is the basic histologic organization of the canine prostate (epithelium vs stroma)?

Answer 33

Secretory epithelial tissue is contained within a stromal capsule of fibrous, elastic, and smooth muscle tissue; smooth muscle septa subdivide it into lobules.

Question 34

How does the histology of a sexually immature canine prostate differ from a mature prostate (high-yield comparison)?

Answer 34

Immature: branching ductular system with undeveloped acini, few lumina, no secretory function, cuboidal-to-flattened basophilic epithelium with high N:C ratio, and more connective tissue. Mature: compound tubuloalveolar glands with dilated alveolar acini, epithelial infoldings, and columnar cells with basal nuclei and eosinophilic apical cytoplasm.

Question 35

At approximately what age do histologic signs of secretory activity typically appear in the canine prostate?

Answer 35

Around 4 months of age.

Question 36

What histologic finding indicates onset of secretory activity in the developing canine prostate?

Answer 36

Eosinophilic material in acinar cell cytoplasm or within the acinar lumen.

Question 37

What two patterns of acinar dilatation are described in mature canine prostates, and what is the key differentiator?

Answer 37

Simple dilatation (many dilated acini ± eosinophilic secretion without compressing adjacent acini) versus focal glandular ectasia (focal sharply demarcated acinar dilatation with compression of adjacent parenchyma).

Question 38

What is the approximate normal pH range of canine prostatic fluid?

Answer 38

Approximately 6.1–6.5.

Question 39

What is the major functional role of canine prostatic secretion in reproduction (high-yield mechanism list)?

Answer 39

It promotes sperm motility/viability, increases uterine perfusion, and modulates neutrophil-induced inhibition of sperm attachment to uterine epithelium.

Question 40

Which ejaculate fraction is classically considered to contain most prostatic fluid in dogs, and what is the common nuance/trap?

Answer 40

Primarily the third fraction, but prostatic contribution may also be present in the first fraction.

Question 41

Which prostaglandin is reported to be released in large amounts from the canine prostate during ejaculation?

Answer 41

Prostaglandin E2 (PGE2).

Question 42

How do sodium, potassium, and chloride concentrations in canine prostatic fluid compare with plasma, and what transport inference is made?

Answer 42

Sodium is similar to plasma (suggesting passive movement), while potassium and chloride are higher than plasma (suggesting active transport).

Question 43

Which trace element is present at high concentration in canine prostatic secretions, where is it localized in epithelial cells, and what is its key proposed effect?

Answer 43

Zinc; localized in nucleolus, nuclear chromatin, and secretory granules; it has an antibacterial effect (role otherwise unclear).

Question 44

Do inflammatory prostatic diseases reliably change zinc concentration, and what does castration do to prostatic zinc concentrations?

Answer 44

Inflammatory diseases do not appear to change zinc concentration; castration causes zinc concentrations to diminish.

Question 45

What are the two main proteins commonly cited in canine prostatic fluid, and which constitutes >90% of total prostatic fluid protein?

Answer 45

Acid phosphatase and canine prostate-specific esterase; prostate-specific esterase constitutes >90% of total protein.

Question 46

Which additional reproductive organ can contribute acid phosphatase, creating a diagnostic trap for ‘prostate-specific’ interpretation?

Answer 46

The epididymis can contribute acid phosphatase in higher concentrations.

Question 47

How do androgen levels relate to prostatic protein concentrations across age, and what pattern is described after ~4 years?

Answer 47

Protein concentrations are androgen controlled and rise with secretory volume until ~4 years, then gradually diminish thereafter.

Question 48

What is the key intraprostatic enzymatic conversion that drives androgen-mediated growth in the canine prostate?

Answer 48

Testosterone is converted to 5α-dihydrotestosterone (DHT) by 5α-reductase within the prostate.

Question 49

At what approximate age does the prostate reach maximum normal cellular content in dogs, and what change is reported beyond that age?

Answer 49

By about 2 years of age; beyond this, benign prostatic hyperplasia (BPH) is reported to develop.

Question 50

What are the two histologically distinct forms of canine BPH and which age groups do they predominate in?

Answer 50

Glandular hyperplasia predominates in younger dogs (<4–5 years); complex hyperplasia is more common after that age.

Question 51

What is the dominant histologic target of glandular hyperplasia and what gross effect does it have on prostate shape?

Answer 51

It is confined to secretory cells (increased number/size), producing symmetric enlargement with orderly architecture.

Question 52

What is the dominant histologic target of complex hyperplasia and what gross effect does it have?

Answer 52

It primarily involves stromal elements and produces asymmetric enlargement with glandular and prominent stromal components (often with stromal atrophy).

Question 53

What is the key ‘trap’ mechanism proposed for increased prostate size in BPH regarding proliferation versus cell death?

Answer 53

Mitotic figures are similar to normal glands, suggesting increased size may be maintained by decreased cell death rather than increased proliferation.

Question 54

How do tissue DHT concentrations change as the prostate enlarges with age, and what receptor-level change is described as a compensatory mechanism?

Answer 54

Tissue DHT concentrations decrease with increasing size, but there are increased numbers of nuclear androgen receptors, increasing responsiveness to androgens.

Question 55

What stromal features are described in complex hyperplasia that can mislead a clinician toward inflammation or neoplasia on imaging?

Answer 55

Cystic alveolar changes with eosinophilic content, lymphocytes/plasma cells, areas of stromal atrophy, and altered vascular flow.

Question 56

What role is proposed for estrogens in canine BPH, and what age-related hormone pattern supports this hypothesis?

Answer 56

Estrogens may increase prostate sensitivity to DHT by inducing nuclear receptors and promoting stromal/collagen synthesis; in aging dogs testosterone and DHT fall while circulating estrogen remains unchanged.

Question 57

What happens to estrogen receptor numbers in canine prostatic carcinoma compared with normal/hyperplastic tissue, and what is the proposed implication?

Answer 57

Estrogen receptor numbers are significantly reduced, possibly contributing to lack of tumor cell differentiation.