Testicular Tumors in Dogs: Vet’s Guide to Detection, Treatment & Prevention 2025  🐶🎗️ 

By Dr. Duncan Houston BVSc

Hello—I’m Dr Duncan Houston BVSc, veterinarian and Ask A Vet founder. Testicular tumors are among the most common tumors in older intact male dogs, especially those >10 yrs and cryptorchid (undescended testicles). This vet-approved guide covers:

• Common tumor types (seminoma, Sertoli, Leydig/interstitial)
• Signs & hormonal changes
• Diagnostics and how vets evaluate lumps
• Treatment options—neutering and further care
• Prognosis and prevention strategies

1. Tumor Types & Frequency

• Interstitial (Leydig) cell tumors: ~50%—usually benign
• Seminomas: ~24%—germ-cell tumors; ~18% occur in cryptorchid testicles
• Sertoli cell tumors: ~18%; often hormone-producing, more common in retained testicles
• Mixed tumors: ~7%—contain multiple cell types

2. Who's at Risk?

• Age: Older intact males (>10 yrs) are most vulnerable
• Cryptorchidism: Undescended testicles carry ~13–16× higher risk, especially for Sertoli and seminoma tumors
• Breed predisposition: Labs, Yorkies, Golden Retrievers, Boxers, German Shepherds, Afghan Hounds, Collies, and Shelties may be overrepresented

3. Clinical Signs

• Palpable lump, enlarged or uneven testicle(s), scrotal swelling
• Hormonal changes: feminization—enlarged mammary glands, nipple growth, hair loss, pigmentation, pendulous prepuce, squatting to urinate
• Systemic signs if metastasis: weight loss, lethargy, anorexia, vomiting

4. Diagnosis by Vets

• Testicle palpation during exams—uneven, firm, or single testicle detected
• Ultrasound, especially for cryptorchid testicles
• Fine-needle aspirate or biopsy, then histopathology after removal
• Additional staging (chest X-ray, lymph node assessment) if malignant suspected

5. Treatment Options

• Orchiectomy (neuter): Standard curative approach for localized tumors, often including scrotal ablation
• Advanced cases: If metastasis is present, consider surgery plus chemo or radiation for aggressive tumor types
• Cryptorchidism cases: Surgically remove retained and other testicles; biopsy critical for diagnosis

6. Prognosis & Follow-Up

• Most tumors are localized and benign—orchiectomy often curative
• Sertoli and seminomas may metastasize—risk ~10–20%
• Post-op monitoring includes incision checks and possibly rechecks at 2 weeks for healing

7. Prevention Strategies

• ✅ Neuter early—prevents tumors entirely, ideally before sexual maturity (~6–12 months)
• 🩺 Manage cryptorchid dogs through early detection and elective removal to reduce cancer risk
• 📆 Regular vet exams—palpation during wellness checks for intact dogs over age 6

📌 Final Thoughts from a Vet

Testicular tumors are common in older, intact male dogs—most are benign and curable with neutering. Early detection through physical exams, prompt treatment, and preventive neutering—especially in cryptorchid dogs—can save lives. For personalized guidance, testicle monitoring reminders, or neuter support, visit AskAVet.com or download our app—because informed care leads to confident pet parenting. 🐾❤️