Phimosis
Ronald M. Bright, DVM, MS, DACVS
BASIC INFORMATION
Description
Phimosis is the inability of the penis to protrude or extend beyond
the prepuce (sheath). This condition is also known as preputial
stenosis.
Causes
Phimosis can be a congenital (present from birth) problem, or it
can arise later in life from scarring around the opening of the prepuce caused by a tumor or trauma. The congenital form may not
be detected for weeks or months.
Clinical Signs
Signs related to the congenital form are dependent on the size of
the opening of the prepuce. The prepuce may be distended, and the
dog may be unable to urinate normally. A small stream of urine or
drops of urine are often seen and may be accompanied by an infection of the prepuce, with discharge of pus from the prepuce. Some
ulceration (raw sores) of the prepuce may be present.
The acquired form that develops later in a dog’s life usually
causes significant inflammation and swelling of the prepuce.
Evidence of a tumor or wound to the prepuce may be present.
With either form of phimosis, licking of the area is a common
sign. In severe cases, urine may build up within the prepuce, causing it to become distended. Animals with phimosis are unable to
breed.
Diagnostic Tests
Close inspection of the prepuce usually defines the problem and
allows an accurate diagnosis to be made. Sometimes, however, a
poorly developed penis or the presence of hermaphroditism may
be confused with phimosis, so these conditions must be ruled out.
An animal that is an hermaphrodite has both ovarian and testicular tissues. Because conflicting sets of hormones are produced, the
external sexual structures may be deformed or underdeveloped.
Specialized testing and/or exploratory surgery of the abdomen (to
look for ovarian and testicular tissue) are needed to make the diagnosis of hermaphroditism.
TREATMENT AND FOLLOW-UP
Treatment Options
If phimosis is caused by inflammation or infection, it may respond
to medical therapy, which can consist of antibiotics, warm compresses applied directly to the prepuce, and insertion of a urinary
catheter for several days.
Phimosis caused by a stricture (narrowing of the preputial opening with scar tissue) or by a tumor is treated with surgery. Surgery
consists of enlarging the opening of the prepuce and removal of
any scar tissue or tumors. Without surgery, a severe and painful
infection of the prepuce may become a chronic problem. A second surgery may be necessary as the dog matures and grows, if
the original one was performed when the dog was very small. If a
tumor is present, additional therapy may be recommended by your
veterinarian.
Follow-up Care
Recheck visits and monitoring are usually needed for some time.
If phimosis is caused by a tumor, then monitoring for recurrence
of the tumor is necessary. Scarring of the preputial opening may
also occur after surgery, and the size of the opening may slowly
decrease. Sometimes, the size of the preputial opening allows the
penis to be extruded but not retracted, and paraphimosis develops.
Paraphimosis can occur if too much tissue is removed from the
prepuce. (See the handout on Paraphimosis in Dogs.)
Prognosis
Animals undergoing surgery usually have a good prognosis. The
need for a second surgery is low unless the original surgery was
performed when the dog was a small puppy.
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