Sperm Duct Cysts in Dogs

Sperm are produced in the testicles. They then travel through the efferent ductules to reach the epididymis, a long tube located in each testicle, where they are stored until being transferred into the urinary tract and excreted. A cyst, called a spermatocele, can form in the epididymis or one of the other sperm ducts. This type of cyst is an accumulation of sperm cells that hardens and blocks the duct. Sperm can no longer travel easily through the duct and often spreads into the surrounding tissue to cause an inflamed area called sperm granuloma. This occurs most commonly in older, male dogs. It is frequently the result of an injury that creates scar tissue in the testicles, but it can also be related to complications and errors during vasectomy. Other contributing factors may be conditions that cause excessive estrogen and any congenital problem that creates blockage in the sperm duct. If a cyst occurs in only one sperm duct, there will often be no symptoms; however when ducts in both testicles become blocked, dogs develop azoospermia, a low number of viable sperm in the semen. Most spermatoceles are diagnosed because of infertility. The chronic, low level inflammation associated with sperm granuloma frequently doesn’t cause pain or other symptoms, but some dogs may also have hard palpable masses on the scrotum. Blockage that is close to the head of the epididymis causes sperm backup into the testicles and is more likely to damage the inner tubules where sperm is produced. There is no effective cure for sperm duct cysts, and most dogs with blockage in both testicles will remain infertile.

Cysts can block the sperm ducts of male dogs leading to low sperm count and infertility. Sperm duct cysts are called spermatoceles. Spermatoceles often cause sperm back-up and create areas of low-level inflammation which are referred to as sperm granuloma. Both of these conditions may make a dog less fertile.