Lecture 81: Reproductive pathology- Male Structure and Function: Non-infectious diseases of the male

Spermatogenic cells

Form spermatozoa via spermatogenesis from germ (stem) cells.

Sertoli cells

Support spermatogenesis; provide nutrients, hormones, cytokines; form blood-testis barrier.

Leydig cells

Produce testosterone; maintain accessory glands, spermatogenesis, and secondary sex characteristics.

Phases of testicular descent

Abdominal translocation → transinguinal migration → inguinoscrotal migration.

Testicular immune privilege

Suppressed immunity due to antigenic sperm outside blood-testis barrier; prevents autoimmune response.

Sperm granuloma

Foreign body reaction to extratubular sperm; leads to chronic inflammation, fibrosis, spermiostasis.

Boar scrotal disease

Hemangiomas; benign, exophytic, may bleed; no fertility impact.

Stallion scrotal trauma

Kick injuries → edema, ulceration, hemorrhage, abscess; may extend from preputial edema.

Ram scrotal dermatitis

Chorioptes bovis infestation; thickened skin, matted wool; may cause testicular atrophy and infertility.

Cryptorchidism

Failure of testicular descent; XY, SRY+ DSD; most common in stallions and tomcats.

Cryptorchidism - consequences

Infertility, ↑ testicular neoplasia (esp. dogs), torsion risk; breeding discouraged.

Cryptorchidism - dogs

Right testis more often retained; descent complete by 3 months; Sertoli tumors in abdominal testes.

Cryptorchidism - cats

Unilateral retention common; Persians overrepresented; inguinal cryptorchidism predominates.

Monorchia

Single testis due to cryptorchidism, degeneration, or rare agenesis; supernumerary testes rare.

Testicular degeneration

Atrophy, mineralization, fibrosis; unilateral = local cause, bilateral = systemic.

Orchitis

Rare; Brucella or TB; most cases diagnosed as orchitis are actually epididymitis.

Tuberculous orchitis

Multifocal granulomatous; rare due to eradication programs.

Brucella orchitis

Can be dominant lesion; epididymitis often more prominent.

Epididymitis - general

Inflammation common; sperm leakage → granulomas; chronic inflammation and obstruction.

Epididymitis - causes

Infectious (Brucella spp., Actinobacillus seminis), congenital ductal disorders, trauma, urine reflux.

Brucella spp. - epididymitis

B. suis, B. ovis, B. melitensis, B. canis; systemic spread → localization in epididymis and accessory glands.

Epididymitis - rams

Brucella ovis in mature rams; Actinobacillus seminis in virgins; tail of epididymis most affected.

Brucella ovis - progression

Local mucosal infection → lymph nodes → bacteremia → genital tract persistence.

Epididymitis - dogs

Brucella canis causes epididymitis, prostatitis, scrotal dermatitis, testicular atrophy.

Epididymitis - cats

Rare; reported with canine distemper virus.

Testicular torsion

Occurs in retained testes; stallions may torsion intrascrotal testis; infarction causes testis loss.

Testicular torsion - presentation

Acute abdominal pain; dark red/black testis; venous infarction; often unrecognizable.

Testicular neoplasia - dogs

Most common species; Sertoli cell tumor, interstitial (Leydig) cell tumor, seminoma.

Sertoli cell tumor - features

White, tough, fibrous; may cause hyperestrogenism and feminization; rare metastasis.

Sertoli cell tumor - signs

Attractiveness to males, gynecomastia, alopecia, squamous metaplasia of prostate, pancytopenia.

Sertoli cell tumor - metastasis

Rare; spermatic cord, lymph nodes; may cause hydrocele and scrotal swelling.

Interstitial cell tumor - features

Yellow, soft, hemorrhagic; slow-growing; often multiple; may cause compression atrophy.

Interstitial cell tumor - hormones

Usually nonfunctional; some produce androgen or estrogen; corrected by removal.

Seminoma - features

White/gray-white, soft, bulging; resembles lymphoid tissue; common in cryptorchid testes.

Seminoma - behavior

Usually benign; metastasis rare but possible; no hormone production.

Scrotal hernia

Abdominal contents enter vaginal sac; congenital or acquired; may cause testicular ischemia.

Scrotal hernia - stallions

Congenital resolves by 3-6 months; acquired may cause strangulation; jejunum often involved.

Prostatic cysts

Congenital or secondary to hyperplasia, neoplasia, inflammation; may become abscesses.

Prostatitis - dogs

Common in older dogs; often with hyperplasia; urinary pathogens; systemic signs and urinary symptoms.

Prostatitis - diagnosis

Cytology and culture of prostatic fluid; hematology often equivocal except in abscesses.

Prostatic hyperplasia - dogs

Testosterone-dependent; affects ≥80% of older dogs; causes obstipation, urinary retention.

Prostatic hyperplasia - complications

Colon obstruction, urethral stretching, hydronephrosis, UTIs; pressure on sacral nerves.

Prostatic carcinoma - dogs

Old dogs; dysuria, stranguria, fecal obstipation, hindlimb issues; metastasis to bone, lymph nodes.

Prostatic carcinoma - spread

Vertebral venous plexus, systemic circulation, direct extension; cells may appear in urine/blood.

Prostatic carcinoma - signs

Asymmetric enlargement, sublumbar extension, hypertrophic osteopathy.

Ulcerative posthitis - sheep

Corynebacterium renale + urea-rich urine; affects wethers; aka pizzle rot.

Ulcerative posthitis - lesions

Yellow necrosis at prepuce orifice → ulceration, stenosis, internal ulceration, urethral process loss.

Ulcerative posthitis - transmission

Contaminated bedding, herbage, flies; venereal from rams to ewes; diet and season influence.

Penile neoplasms - bulls

Fibropapillomas from bovine papillomavirus 1; young bulls; hemorrhage post-mating.

Fibropapillomas - complications

Interfere with penile movement; may cause strangulation by preputial hairs.

Penile SCC - horses

Equus caballus papillomavirus 2 implicated; firm, ulcerated tumors; often arise from papilloma sites.

Penile SCC - species

Horses (stallions and geldings), dogs, bulls; average age >12 years in horses.

Persistent frenulum - bulls

Congenital defect; failure of separation of penile tissue; may interfere with breeding.

Testicular descent - species timing

Complete descent usually occurs before birth in most species; exception: dog (postnatal descent).

Cryptorchidism - inheritance

May be inherited (e.g., autosomal recessive in dogs); breeding discouraged due to heritability.

Cryptorchidism - neoplasia risk

↑ risk of Sertoli cell tumors (abdominal retention) and seminomas (inguinal retention).

Cryptorchidism - associated defects

Patellar subluxation, hip dysplasia, penile/preputial defects, umbilical/inguinal hernias.

Cryptorchidism - stallions/tomcats

Most common genital abnormality; testis may be anywhere along descent path.

Monorchia - causes

Cryptorchidism, unilateral degeneration, or rare agenesis; differentiation from degeneration is difficult.

Polyorchidism

Rare condition with supernumerary testes or fusion of abdominal testes.

Testicular degeneration - gross signs

Atrophy, mineralization, fibrosis; may be uni- or bilateral depending on cause.

Orchitis - primary agents

Brucella abortus, tuberculosis; rare due to eradication; often misdiagnosed as epididymitis.

Epididymitis - sterile causes

Congenital ductal disorders, adenomyosis, trauma, urine reflux; sperm granulomas may form.

Brucella - epididymitis pathogenesis

Mucosal contact → systemic spread → localization in epididymis and accessory glands.

Brucella ovis - lesion location

Tail of epididymis most commonly affected; hallmark of infection.

Testicular torsion - stallions

Spontaneous torsion of intrascrotal testis causes colic; exception to cryptorchid-only torsion rule.

Testicular torsion - dogs

Often associated with neoplasia; infarction leads to loss of spermatogenesis.

Testicular neoplasms - classification

Sex cord-stromal (Sertoli, Leydig), germ cell (seminoma), mixed germ cell-stromal (rare).

Sertoli cell tumor - hormone effects

Hyperestrogenism → feminization, pancytopenia, prostate changes; larger tumors more likely to produce hormones.

Sertoli cell tumor - gross appearance

White, tough, solid or cystic; multinodular, lobulated; fibrous stroma gives firmness.

Interstitial cell tumor - gross appearance

Yellow, soft, greasy; hemorrhagic, cystic; well-demarcated, spheroidal; often multiple.

Interstitial cell tumor - behavior

Slow-growing, compressive; rarely invasive; may reduce fertility in bulls.

Seminoma - gross appearance

White or gray-white, soft, bulging; resembles lymphoid tissue; tan in stallions.

Seminoma - metastatic potential

Usually benign; metastasis possible but unpredictable; no hormone production.

Scrotal hernia - pathogenesis

Failure of inguinal ring closure, vaginal process obliteration, muscle weakness, or ↑ intra-abdominal pressure.

Scrotal hernia - congenital vs acquired

Congenital resolves by 3-6 months; acquired may cause strangulation and testicular ischemia.

Prostatic cysts - types

Retention cysts, hyperplasia-associated cysts, squamous metaplasia cysts; may become abscesses.

Prostatitis - clinical signs

Systemic illness, urinary signs (hematuria, pyuria, discharge, dysuria); often in older dogs.

Prostatic hyperplasia - prevalence

Very common in older intact dogs; testosterone-dependent; ≥80% affected.

Prostatic carcinoma - age group

Mostly in dogs >10 years; mimics other prostatic diseases; aggressive and metastatic.

Prostatic carcinoma - metastasis sites

Iliac/pelvic lymph nodes, bone, kidneys, bladder, lungs, liver, heart, mesentery, omentum.

Prostatic carcinoma - unique signs

Hindlimb weakness, emaciation, hypertrophic osteopathy; neoplastic cells in urine/blood.

Ulcerative posthitis - pathogenesis

Corynebacterium renale + urea-rich urine; epithelial necrosis → ulceration → stenosis.

Ulcerative posthitis - risk factors

Wethers, high-protein/legume diets, contaminated bedding, flies; venereal transmission possible.

Ulcerative posthitis - lesion progression

Starts at preputial orifice → internal ulceration → urethral process destruction → penile head ulceration.

Fibropapilloma - bulls

Bovine papillomavirus 1; young bulls; hemorrhage post-mating; may cause penile strangulation.

Squamous cell carcinoma - horses

Equus caballus papillomavirus 2 implicated; firm, ulcerated tumors; often arise from papilloma sites.

SCC - penile location

Head of penis; desmoplastic reaction enlarges and hardens tissue; ulceration and necrosis common.