Lecture 18- Canine Male Infertility

Testicular descent timeline

Testes should be scrotal by 10 days postpartum; both descended by 16 weeks; not cryptorchid until 6 months; inguinal canal closes at 6 months

Cryptorchidism genetics

Sex‑limited autosomal recessive; breed predispositions exist

Cryptorchidism diagnosis

hCG stimulation test (500 IU small/medium, 1000 IU large breeds); baseline testosterone then 4 hr and 8 hr post‑hCG should >2× baseline; AMH test detects testicular tissue (sometimes inconclusive)

Testicular torsion

Rare; extremely painful; treat with bilateral orchidectomy; autoantibodies form within 4 hrs → sterility risk

Testicular tumors prevalence

2nd most common male tumor; Sertoli 44% (most common), seminoma 31%, Leydig 25%

Sertoli cell tumor features

Bilateral in 45%; estrogen secretion → feminization; pancytopenia; anemia; bilateral symmetrical alopecia; hyperpigmentation; dry skin; gynecomastia; prostatitis; pendulous prepuce; bone marrow hypoplasia

Differentiate Sertoli tumor vs Brucella

Sertoli tumors: non‑painful, ultrasound/biopsy confirm; Brucella: painful epididymitis/orchitis

Tumors in scrotal testis

All cause enlargement; Sertoli causes contralateral testicular atrophy; multiple tumors may occur in one testis

Tumors in retained testis

Cryptorchidism increases tumor incidence 13.6× overall, 23× for Sertoli tumors

Hyperestrogenism signs

Alopecia; comedones; hyperpigmentation; pendulous prepuce; testicular atrophy; prostatic cysts; gynecomastia

Azoospermia definition

No sperm in ejaculate

Oligospermia definition

Low sperm count

Azoospermia cause: retrograde ejaculation

Diagnose via urinalysis by cystocentesis after ejaculation

Azoospermia cause: incomplete ejaculation

ALP <5000 U/L in seminal fluid (true for dogs and stallions)

Azoospermia pretesticular causes

Hypopituitarism, hypothyroidism, hernia, glucocorticoid excess; tests: LH/FSH ↓, free T4 ↓, cTSH ↑, ACTH stim/dex suppression

Azoospermia testicular causes

Intersex animals; karyotype (78, XY); ALP >5000 U/L

Azoospermia: germinal cell aplasia

Testicular biopsy (only Sertoli cells); ALP >5000 U/L

Azoospermia: bilateral cryptorchidism

Physical exam; hCG test; AMH

Azoospermia: testicular injury

Semen culture; Brucella serology; seminal cytology; ALP >5000 U/L

Azoospermia: autoimmune orchitis

ALP >5000 U/L; biopsy

Azoospermia: spermatogenic arrest

ALP >5000 U/L; biopsy

Azoospermia: testicular neoplasia

Physical exam; ultrasound; biopsy

Azoospermia post‑testicular causes

Segmental epididymal aplasia; sperm granuloma; ALP <5000 U/L; epididymal ultrasound; exploratory surgery

Sperm requirement for fertility

200 million progressively motile spermatozoa needed for good conception rates

TVT characteristics

Penis/prepuce/vagina/nasal mucosa; transmitted via mucous membrane contact; chromosome number 59±5 (vs dog 78); treat with vincristine; SCC is differential

TVT cytology

Round cells; more cytoplasm than lymphoma; resembles histiocytoma; diagnosis relies on LOCATION

Urethral prolapse

Genetic in English Bulldogs; idiopathic or arousal‑induced; “red pea” appearance; treat surgically

Priapism

Persistent erection; rare; usually neurologic; evaluate for spinal/back disease

BPH prevalence

Most common prostatic disease; older intact males (~8 yrs); can occur in androgen‑treated castrated males

BPH clinical signs

Serous/serosanguinous urethral discharge; hematuria; dysuria; tenesmus; caudal abdominal pain; infertility; constipation with flat feces

BPH palpation findings

Smooth, bilobed, symmetrical, non‑painful; homogeneous consistency

Prostate position changes

Young dogs: pelvic floor; older dogs: cranial abdominal; must elevate prostate to palpate in older dogs

BPH differential: acute prostatitis

Fever, depression, pain on palpation, neutrophilia, pyuria, bacteriuria; often concurrent with BPH

BPH differential: chronic prostatitis

Recurrent UTIs; may coexist with BPH

BPH differential: prostatic adenocarcinoma

Weight loss, hind limb weakness, dysuria, hematuria, dyschezia; carcinoma cells in urine sediment

BPH differential: prostatic/paraprostatic cysts

Palpable abdominal cystic mass with yellow/orange fluid

Prostatic disease diagnosis

Palpation; CBC; semen/urine cultures; prostatic wash; ultrasound; radiographs; FNA; biopsy

Prostatic wash cytology

BPH: uniform cells; neoplasia: variable cells; septic: inflammatory cells; E. coli most common prostatitis pathogen

Prostate ultrasound: BPH

Symmetrical; mild enlargement; mottled; small parenchymal cysts

Prostate ultrasound: acute prostatitis

Symmetrical; mottled; hypoechoic areas; concurrent cystitis

Prostate ultrasound: chronic prostatitis

Symmetrical/asymmetrical; poorly marginated; mixed echogenicity; mineralization possible

Prostate ultrasound: neoplasia

Asymmetrical; heterogeneous; hyperechoic foci; distorted architecture; large fluid cavities

Prostate ultrasound: abscess

Asymmetrical; mottled; echogenic fluid

Prostate ultrasound: paraprostatic cyst

Adjacent to prostate; thin‑walled; resembles second bladder

BPH treatment: finasteride

5α‑reductase inhibitor; dose 0.1–1 mg/kg daily; takes 3–4 months; monitor liver values

BPH treatment: DES

Short course reduces prostatic secretion for up to 2 months; used when castration not an option

BPH definitive treatment

Castration

Sexual behavior post‑castration

May persist months–years; brain masculinization occurs prenatally; dogs may still mount/copulate up to 8 months post‑castration; cats may intromit up to 5 years