The first is called a spermatocele. This type of cyst forms when a fault or blockage is present in the epididymis. This causes sperm to escape and collect into the surrounding areas, forming a smooth lump that can vary in size. While normally harmless, the spermatozoa can cause the immune system to generate a foreign body response. This leads to inflammation, building pressure, and the potential for rupture. A rupture can become infected and pose a health threat to the cat.

The second type of sperm duct cyst is called a spermatic granuloma. These cysts form when the epididymis has not properly joined to the vas deferens in development. Spermatozoa will spill out of the end of the duct, collecting until a cyst forms. Often there is only one large cyst present, however numerous cysts can occur. If both epididymides are affected, no sperm will be present in the semen and the cat will be infertile. 

Epididymides are the narrow tubes that carry sperm from the testicles to the vas deferens. A number of issues can cause cysts to form within these ducts. Two main types of cyst may form in or around the epididymis tube. 

Cysts of the epididymides are often only found after the cat has proven unable to breed. Most cats do not show symptoms unless a rupture has occurred. Possible symptoms are as follows:

Any issue that affects the epididymides of the cat can potentially lead to spermatozoa spillage and cyst formation. External factors can lead to this problem, or the cat may present with issues from birth. Known causes include:

You will be asked to bring the cat’s full medical history to a veterinary appointment if epididymal issues are suspected. The veterinarian will perform a complete physical examination of the cat to check for cysts in the testicular area. Any underlying causes will also be checked for. A semen sample may be needed to see if ejaculation is incomplete. Any tenderness or the presence of lesions should be noted.

Blood work should be collected including a complete blood count and a biochemical profile. This will give the veterinarian an overview on the cat’s general health. Urinalysis can be very useful in identifying any bacteria if an infection is present. An ultrasound may be used to confirm the location and number of cysts in the sperm ducts. A biopsy may be taken to verify if the cyst is malignant, although this is rare. The cat may also need to have a preanesthetic check-up to make sure it is healthy enough to undergo surgery if deemed necessary.

Treatment is only necessary when fertility has been affected or infection or disease are present in the cyst. Many cats live with undiagnosed sperm duct cysts for their entire lives. 

To remove a cyst of the epididymis, an incision is made in the area of the cyst. The cyst is then fully drained and removed. The tissue collected from the excision will be sent to a lab for further examination. The cat will need to be under general anesthesia for the procedure. Painkillers will be prescribed upon discharge, as the surgery can be very painful.

If a serious issue, such as cancer, is discovered while evaluating a cyst, the removal of the male reproductive system may be necessary to ensure good health to the cat. This is a routine surgery, however, the underlying disease may cause complications.

If the cat has undergone surgery, or if an infection was confirmed, antibiotics will be prescribed to rid the body of harmful bacteria. These prescriptions generally last one to four weeks.

If surgery has been performed on your cat, certain at-home care measures must be taken. Keep the incision site clean and prevent your cat from licking, biting or scratching at its stitches. An Elizabethan collar may help with this. Continue the administration of all prescribed medications and antibiotics as per request by your veterinarian. The cat will often be scheduled to have a postoperative appointment to assess healing.

If the cat has been fully neutered, no more issues should remain, although the cat will be left permanently sterile. If the cyst has been successfully removed, fertility may be restored. This is not guaranteed, as some problems that cause epididymal cysts to form create infertility themselves, and surgical complications can leave the ducts damaged.