Dog: Orchitis

General information

Other common/scientific names: epididymitis

In the male dog, the testicles are responsible for production of sperm cells and the male hormone, testosterone. The testicles are housed in the scrotum which is the external sac of skin. The epididymis is the structure attached to the testicles where the final maturation of sperm occurs. The vas deferens is the tubular duct which carries the sperm from the epididymis to the penile urethra (the tube which carries urine from the bladder) during ejaculation. The prostate is an accessory sex gland which produces the fluid portion of the sperm.

Orchitis is defined as inflammation of the testicles and can also include the epididymis, vas deferens and prostate. It can involve one or both testicles. Inflammation can cause increased temperature in the testicle. This ensuing hyperthermia combined with the inflammation causes damage to the sperm producing cells in the testicles resulting in infertility. Orchitis can be acute (sudden) or chronic (lasting).


Orchitis is caused by trauma, infection (fungal, bacterial or viral) or testicular torsion (twisting). Bacterial infections are usually a result of an ascending infection starting in the urinary tract or prostate. Trauma to the testicles can cause an immune-mediated orchitis where the body’s own immune system causes the inflammation and testicular damage. Specific diseases known to cause an orchitis are brucellosis, canine distemper virus, blastomycosis, coccidioidomycosis, ehrlichiosis and Rocky Mountain spotted fever.

Cardinal symptom

Swollen testicle(s)


Dogs with acute orchitis have swollen, painful testicles. The scrotum is warm to touch and reddened. Some dogs will lick the scrotum excessively creating skin abrasions. The dog may walk stiffly due to pain. In severe cases, dogs will develop a fever and loss of appetite.

Dogs with chronic orchitis are not usually painful. The main clinical sign in these cases is infertility.


Diagnosis is made by physical examination. Ultrasonography should be performed on any dog with an enlarged testicle to rule out testicular cancer. A rectal examination of the prostate should be performed. Additional tests may be required to aid in identification of the cause. These include a complete blood count (CBC), serum biochemistry and urinalysis with culture and sensitivity. In breeding males, a complete examination of an ejaculate may be necessary.


Treatment of orchitis consists of systemic antibiotics and pain medication. Anti-inflammatory medications can help reduce inflammation in the testicles. Cold packs applied to the injured testicle(s) help reduce the hyperthermia. Immunosuppressive drugs may be needed in cases of immune mediated disease. Castration is recommended in cases due to brucellosis or severe testicular damage. In breeding males, if only one testicle is affected, this testicle can be removed to preserve the normal testicle and fertility of the male.


Mild cases of orchitis involving only one testicle have a good chance of recovery and return to fertility. However, severe cases involving both testicles or chronic cases usually result in permanent damage to the testicular tissue.


Orchitis is prevented by castration.

Update version: 4/24/2014, © Copyright by
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