Dog Testicle or Scrotum Swollen: Pain, Infection, or a Lump?
General guidance — not a diagnosis. When in doubt, call your vet.
A new swelling needs an examination
A swollen testicle or scrotum is a sign, not a diagnosis. Arrange a veterinary examination; seek emergency care for sudden severe pain, rapidly increasing swelling, or a dog who is becoming unwell. Do not squeeze the area to work out what is inside.
Testicular or epididymal inflammation can cause painful swelling. [1] A lump does not automatically mean cancer: ultrasound findings overlap between different testicular diseases. [2]
Skin swelling or a change inside?
The scrotum is the skin pouch around the testicles. Tell the vet whether the change seems to involve the skin, the whole pouch, or one side more than the other. Do not repeatedly palpate a painful area.
Useful details include redness, a visible wound, bruising, discharge, licking, reluctance to sit, and whether swelling started abruptly or developed gradually. Record whether your dog is intact, recently neutered, or has a history of an undescended testicle. These observations help guide the examination; none confirms the cause.
Discharge from the opening of the sheath is a separate observation from swelling of the scrotum. If that is also present, describe it separately using the distinctions in dog preputial discharge. Mention changes in urination or straining to pass stool as well; prostate disease signs are another useful history checklist, not a diagnosis for the swelling.
What the vet may investigate
Ultrasound can assess lesions and blood flow, but it does not by itself identify every tumor type. [2]
A twisted testicle can lose blood supply and develop tissue damage. [2] That is why sudden painful swelling should not be watched at home while waiting for it to settle.
Brucella canis is one infectious possibility, not an explanation for every swollen scrotum. It can cause reproductive disease in dogs and infect people. [3] Tell the clinic about breeding, imported-dog history, and known contact with infected dogs before your visit.
Safe steps while arranging care
Keep your dog quiet and stop breeding until the cause is assessed. If licking is persistent, ask the clinic whether a protective collar is appropriate. Take a photo without restraining or manipulating the painful area, and note the last normal urination.
Do not drain a lump, apply harsh antiseptics, or give human painkillers or leftover antibiotics. If swelling follows neutering, contact the operating clinic and describe the change rather than assuming it is routine healing.
If brucellosis is suspected or confirmed, follow the clinic's contact precautions. CDC guidance includes gloves for handling urine or feces and thorough handwashing after exposure. [3]
When to See a Vet
- Emergency now: sudden marked swelling with crying, guarding, or inability to settle.
- Emergency now: swelling with collapse, profound weakness, or repeated vomiting.
- Emergency now: repeated attempts to urinate with little or no urine.
- Prompt veterinary appointment: a new painless lump, persistent asymmetry, redness, a wound, or ongoing licking; call the operating clinic for new swelling after neutering.
For dog owners
An article can't ask about your dog.
Describe what you're seeing. You'll get a few follow-up questions about your dog, then where it lands — vet today, watch closely, or no visit needed — and what to do at home meanwhile.
Frequently Asked Questions
Can I wait if my dog is not in pain?
Book an examination for a new lump or change in size. Comfort alone does not tell you what the swelling is; seek urgent care if pain or illness develops.
Does a swollen testicle mean cancer?
No. Different testicular diseases can have overlapping ultrasound appearances, and ultrasound alone does not identify every tumor type. [2]
Can this infection spread to people?
Some causes can. Brucella canis can infect people, so suspected infection needs veterinary guidance on contact precautions. [3]
Should I put cream on the swollen skin?
Ask the clinic first. Avoid experimenting with creams or disinfectants, particularly on a wound or an area your dog can lick.
What should I tell the clinic?
Describe onset, pain, skin changes, urination, neuter status, and any recent procedure or injury. Mention breeding and known infectious contacts before arrival.
References
- Davidson AP. Orchitis and Epididymitis in Dogs and Cats. Merck Veterinary Manual, professional version. 2025.
- Bracco C, Gloria A, Contri A. Ultrasound-Based Technologies for the Evaluation of Testicles in the Dog: Keystones and Breakthroughs. Veterinary Sciences. 2023.
- Centers for Disease Control and Prevention. Veterinary Guidance for Brucellosis. 2024.