Initial treatment and further evaluation
Since all physical and laboratory data pointed to a diagnosis of benign prostatic hyperplasia, we decided to further evaluate
the possibility of this disease before proceeding with more invasive diagnostic testing. With that in mind, a sample for a
baseline testosterone concentration was submitted. While awaiting these results, we instituted antimicrobial therapy with
enrofloxacin (5 mg/kg orally b.i.d.) empirically to treat a possible undetected prostatitis. We chose enrofloxacin for its
excellent distribution into the prostate gland. We discontinued the antibiotic therapy after one week since the blood-tinged
preputial discharge continued despite therapy.
Figure 2: An ultrasonogram obtained on admission. Note the mostly uniform echotexture of the prostatic parenchyma. The white
arrow indicates a small cyst in the dorsal prostate.
One week after our initial evaluation, the baseline testosterone concentration returned as 2,747 pg/ml (reference range for
castrated dogs < 50 pg/ml; reference range for cryptorchid dogs 100 to 500 pg/ml; reference range for intact dogs > 1,000
pg/ml). Satisfied that this dog was producing a testosterone concentration adequate to predispose the dog to benign prostatic
hyperplasia, we decided to perform a laparoscopic evaluation of the abdomen to attempt to identify an intra-abdominal testicle
and obtain a prostatic biopsy sample. Preoperatively, an electrocardiogram showed intermittent atrial premature contractions;
however, echocardiography revealed no evidence of heart chamber enlargement or valvular insufficiency.
At laparoscopy, both vasa deferentia were seen, as was the left inguinal ring. A vascular bundle that traversed the left inguinal
ring appeared to be thrombosed, but there appeared to be no vas deferens exiting this side. No structures were seen traversing
the right inguinal ring. The left vas deferens was followed for about 4 cm from its approximated urethral insertion, where
the vas deferens ended abruptly. The right vas deferens was followed about 5 cm from its approximated urethral insertion,
at which point a small mass of tissue was identified. This mass was externalized through a trocar site located about 2 cm
paramedially to the midprepuce on the right side. It was removed along with about 3 cm of the right vas deferens and submitted
for histopathologic examination. The regions of the prostate seen laparoscopically revealed no gross abnormalities; however,
only the right lobe of the prostate was isolated (through blunt dissection). Several samples of the prostate were obtained
with a Tru-Cut biopsy needle and submitted for histopathologic examination as well.
Anesthetic recovery was normal, and the dog was discharged the next day pending histopathologic examination of both the prostatic
biopsy samples and the mass removed from the distal end of the right vas deferens. Carprofen (2.2 mg/kg orally b.i.d. for
three days) was dispensed for postoperative pain relief.
Histopathologic examination of the prostatic biopsy samples revealed mild plasmacytic prostatitis with well-differentiated
prostatic glands; no evidence of cysts, infection, or neoplasia was noted. The microscopic appearance of the biopsy samples
was consistent with benign prostatic hyperplasia. Examination of the right-sided mass at the tip of the vas deferens revealed
focal lymphocytic-plasmacytic cellulitis with mineralization and connective tissue. No testicular tissue was seen in this
Given our biopsy confirmation of benign prostatic hyperplasia and prostatitis and lack of evidence of a retained intra-abdominal
testicle, we decided to perform provocative testing to further evaluate the presence of retained testicular tissue. We performed
a human chorionic gonadotropin (HCG)-response test (Table 4) to support our concern that this dog had viable testicular tissue that was producing the testosterone needed to cause benign
prostatic hyperplasia. The response to HCG seen in this patient thus prompted us to resume our search for an undescended intra-abdominal
testicle that had evaded laparoscopic exploration or, less likely, an extratesticular source of testosterone.
Table 4: Endocrinologic Testing Results