Testicular Swelling in Dogs

Epididymitis/Orchitis in Dogs

Epididymitis is inflammation of the testicular tube where sperm is stored, while orchitis is inflammation of the testes themselves. While the condition can be chronic, acute forms caused by direct trauma to the scrotum are more common. Epididymitis is commonly diagnosed in dogs, generally striking in the adult years; the average age of dogs affected with this condition is four years old. Breed does not indicate the probability of a dog being affected.

The condition or disease described in this medical article can affect both dogs and cats. If you would like to learn more about how this disease affects cats, please visit this page in the PetMD health library.

Symptoms and Types

The symptoms of epididymitis and orchitis can be localized in the area of the scrotum. These include:

  • Swollen testicles
  • Licking of the scrotum and scrotal skin irritation (dermatitis)
  • Non-localized symptoms include pain and fever
  • Unwillingness to walk and general lethargy
  • Open wound may be found
  • Refusal to eat is not uncommon
  • Infertility is commonly seen in dogs with this condition


Acute forms of this condition are most often caused by trauma to the scrotum. Epididymitis and orchitis can also be triggered by infectious organisms, as well as by other conditions, including viral causes (i.e., distemper), infections associated with inflammation of the prostate (prostatitis) and inflammation of the bladder (cystitis). Bite wounds on any area of the body can also lead to the development of epididymitis or orchitis.


Your veterinarian will perform a thorough physical examination on your dog, taking into account the background history of symptoms and any possible incidents that might have played a role in its onset. Other potential causes of the above mentioned symptoms include hernia of the scrotum, scrotal dermatitis, twisting of the spermatic cord, sperm-filled mass of inflamed tissue (granuloma), fluid-filled sacks on the spermatic cord (hydrocele), prostatitis, cystitis, and abnormal cell growth (neoplasia). Before treatment can begin, all of these condtions must first be ruled out.

White blood cell counts may be high in cases of infectious orchitis. If the root cause is prostatitis or cystitis, a urinalysis will likely reveal blood, pus, or excess proteins in the urine. Antibody testing should determine if an infectious organism is at the root of the problem. Ultrasounds of the prostate, testes, and epididymis may also be performed to rule out other causes.

If an open wound is present, it should be checked for bacterial infection. A bacterial culture may also be taken of the prostate, as well as of the fluid in the testes. Semen should also be collected and tested.

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