Dog Testicular Swelling - Causes, Diagnosis & When to See a Vet
> Disclaimer: This article is for informational purposes only and is not a substitute for professional veterinary advice, diagnosis, or treatment. Always consult your veterinarian with questions about your dog's health.
Quick Summary
Testicular swelling in dogs can stem from infection, trauma, torsion, or cancer. Intact male dogs are at risk, and some causes require urgent care. Early veterinary evaluation and treatment—often including neutering—improve outcomes and prevent serious complications.
What Does Testicular Swelling Look Like in Dogs?
Swelling may affect one or both testicles and can develop gradually or suddenly.
Signs to watch for:- Enlarged testicle(s) — One or both larger than normal
- Asymmetry — One side noticeably bigger than the other
- Redness or warmth — Inflammation or infection
- Pain — Dog licks the area, is reluctant to sit or move
- Firm or hard texture — May suggest tumor or torsion
- Skin changes — Ulcers, scabs, or discharge
- Lethargy, loss of appetite — Especially with infection or cancer
- Abdominal pain or straining — If torsion or severe inflammation
Common Causes of Testicular Swelling in Dogs
- Testicular torsion — The testicle twists, cutting off blood supply. Accompanying: acute pain, vomiting, shock. Susceptible: retained testicles (cryptorchid). Emergency.
- Orchitis/epididymitis — Infection or inflammation of the testicle or epididymis. Accompanying: pain, fever, lethargy. Can be bacterial (e.g., Brucella, E. coli) or immune-mediated. Intact males.
- Testicular tumors — Most testicular tumors in dogs are benign (e.g., Sertoli cell, seminoma) but can produce hormones and metastasize in some cases. Accompanying: swelling, sometimes symmetric (both sides), hair loss, mammary enlargement. Susceptible: cryptorchid dogs have much higher risk. Older intact males.
- Trauma — Blunt force, bite wounds, or injury. Accompanying: bruising, wounds, pain. May lead to infection or hematoma.
- Scrotal hematoma — Blood collects in the scrotum after trauma or surgery. Accompanying: swelling, bruising, discomfort. Usually resolves with rest and cold compresses; severe cases need drainage.
- Epididymal cyst — Fluid-filled sac; usually benign. Accompanying: smooth, sometimes fluctuant swelling. No systemic signs.
- Cryptorchidism complications — Retained testicle in abdomen can torsion, develop tumors, or cause pain. Susceptible breeds: Chihuahua, Pomeranian, Yorkshire Terrier, Miniature Schnauzer.
- Brucella canis — Bacterial infection causing orchitis and epididymitis. Contagious to other dogs; zoonotic. Accompanying: intermittent lameness, back pain, infertility. Testing required.
- Prostatic disease — Enlarged or infected prostate can cause referred discomfort or secondary swelling. Accompanying: straining to defecate, blood in urine. Older intact males.
- Allergic or contact dermatitis — Scrotal skin reacts to allergens or irritants. Accompanying: itching, redness, possible secondary infection. Less common cause of true testicular enlargement.
When Is Testicular Swelling an Emergency?
Seek emergency care if your dog has:
- Sudden, severe swelling with obvious pain or vocalization
- Vomiting, collapse, or shock — Possible torsion
- Bite wounds or open injuries to the scrotum
- Swelling that is rapidly worsening
- Inability to urinate or severe straining
- Fever (over 103.5°F) with swelling and lethargy
How Veterinarians Diagnose the Cause
Your vet will perform a careful physical exam, including palpation of the testicles and scrotum.
Diagnostic steps:- Physical examination — Size, symmetry, consistency, pain response
- Ultrasound — Evaluates blood flow, structure, masses, torsion
- Fine-needle aspirate or biopsy — For masses, to distinguish tumor types
- Brucella canis test — Blood or PCR, especially in breeding dogs or those with orchitis
- Blood work — Infection indicators, hormone levels if tumor suspected
- Abdominal imaging — If cryptorchid; retained testicle may be in abdomen
- Urinalysis — If prostatic or urinary involvement suspected
Treatment Options
Treatment depends on the cause.
Testicular torsion: Emergency surgery to remove the affected testicle (orchiectomy). Often both testicles are removed (neutering). Orchitis/epididymitis: Antibiotics (based on culture if possible), anti-inflammatories, sometimes neutering if chronic or severe. Brucella-positive dogs need specific protocols and breeding restrictions. Testicular tumors: Orchiectomy (neutering) is curative for most benign tumors. Cryptorchid dogs need removal of both abdominal and scrotal testicles. Follow-up for malignant types. Trauma: Wound care, antibiotics if infected, pain medication. Severe hematoma or necrosis may require surgery. Scrotal hematoma: Rest, cold compresses, pain relief. Drainage or surgery if large or infected. Cryptorchidism: Neutering with removal of both testicles (including the retained one) to prevent torsion and tumors. Brucella canis: Long-term antibiotics; often neutering. Quarantine and testing of other dogs. Zoonotic precautions for handlers.Neutering prevents testicular tumors, torsion, and reduces some behavioral and prostate issues.
Prevention Tips
- Neuter your dog — Eliminates testicular disease risk; consider early neutering unless breeding
- Check cryptorchid dogs — Ensure both testicles descended; neuter if one or both retained
- Avoid trauma — Supervise around other dogs; prevent access to hazardous areas
- Brucella testing — For breeding dogs; quarantine new animals until tested
- Routine exams — Early detection of masses or swelling