TL;DR: If your dog has a swollen testicle, it usually indicates inflammation, infection, or a tumor and requires veterinary evaluation within 24 to 48 hours. Seek immediate care if your dog shows signs of extreme pain, lethargy, or vomiting.
What causes one testicle to be larger than the other in my dog?
Noticing that your dog has one testicle significantly larger than the other is usually a sign of an underlying medical condition rather than a natural variation. Common causes include:
- Orchitis (inflammation often due to infection)
- Epididymitis
- Testicular Neoplasia (tumors)
- Physical trauma to the area
How quickly should I take my dog to the vet for testicular swelling?
The urgency level for a swollen testicle is classified as Medium. While this is rarely a life-threatening emergency in the first few hours, you should aim to have your dog evaluated by a veterinarian within 24 to 48 hours. Seek veterinary care sooner if your dog shows any of the following:
- Signs of extreme pain
- Lethargy
- Persistent vomiting
- An area that is hot to the touch
How does taking a photo of my dog's swelling help with veterinary triage?
Taking a clear photo of the affected area can be incredibly beneficial for your veterinary team or a triage assistant. A visual record allows professionals to:
- Assess the degree of enlargement
- Look for skin discoloration or bruising
- Check for any visible discharge
- Determine the severity and prioritize your dog's appointment appropriately
Clinical Context (Merck Veterinary Manual)
When evaluating a dog with one testicle appearing much larger than the other, diagnostic considerations should include testicular torsion, focal lesions such as masses or abscesses in the testis or epididymis, scrotal hernia, and hematoma. Diagnostic tests should include evaluation for Brucella canis infection and semen analysis with bacterial and mycoplasmal culture. Testicular or epididymal specimens for cytology and culture may be obtained by fine-needle aspiration. Testicular biopsy for histopathology and bacterial culture may be performed if needed, after less invasive diagnostic tests have been completed; however, epididymal aspiration and biopsy are rarely done due to the risk of granuloma formation. Careful palpation of the testes and epididymides for symmetry and normalcy is warranted, and abnormalities justify ultrasonographic evaluation. The scrotum should also be evaluated for evidence of dermatitis or trauma. Cryptorchidism, where one or both testicles are not present in the scrotum by puberty, should also be considered, although this typically presents as an absence of a testicle rather than a size difference.
Chapter: Urology, Infectious Diseases, Diagnostic Imaging, Reproduction
Source: The Merck Veterinary Manual, 11th Edition (Page 1400)