Case information:
You are presented with a 6 year old intact male Lhasa Apso. He is a proven sire and most recently sired a litter 3 months ago. When used for breeding last week, he appeared reluctant to mount the bitch and bloody fluid dripped from his prepuce for a time after the copulatory lock, or tie, was complete.
On physical examination, rectal temperature, pulse and respiratory rate all are within normal limits. The testes are normal in consistency and size and are symmetrical. The caudal portion of the prostate is just barely palpable per rectum; the dog cries out when pressure is applied to the prostate. All else is normal.
You collect 3 ml of semen with the appearance shown below. There are few spermatozoa in the sample. Serology for canine brucellosis is negative.
Question:
What are your primary rule-outs for this dog?
Answer:
Prostate disease is the most likely cause of hemospermia, or blood in the ejaculate. Frank blood also may be seen with penile trauma but that usually is readily diagnosed on physical examination and would not be associated with pain. Signs of pain in this dog include reluctance to mount an estrous bitch and direct pain response when pressure is put on the prostate. The most likely rule-out at this point is acute prostatitis. Remember that prostate infection usually occurs secondary to some underlying prostate disease, with benign prostatic hypertrophy the most common.
Question:
What diagnostics can you perform to definitively diagnose this dog's problem and to guide treatment?
Answer:
Culture of seminal fluid - Remember that there are bacteria in the distal urethra that will contaminate every ejaculated semen sample. Growth of greater than 100,000 colony-forming units (CFU) of bacteria per ml of semen is significant.
Culture of prostatic tissue - This is best retrieved by fine-needle aspirate of the prostate, most commonly and safely performed with ultrasound guidance.
Prostatic ultrasound - This may allow differentiation of uncomplicated benign prostatic hypertrophy (diffuse, uniform prostatic enlargement) from prostatitis (mottled parenchyma) or prostatic neoplasia (mottled, calcified parenchyma). Cytology of an aspirated sample more readily permits definitive diagnosis than does gross appearance of the prostate, with biopsy superior to fine-needle aspirate.
Case Outcome:
Prostatic ultrasound is below. Aerobic culture revealed growth of greater than 100,000 CFU/ml Pasteurella multocida, sensitive to amoxicillin, ampicillin, amoxicillin-clavulanate, erythromycin, tetracycline, enrofloxacin, ciprofloxacin, trimethoprim-sulfa, and cephalexin.
Question:
What is your diagnosis? How will you treat this dog?
Answer:
The diagnosis is acute prostatitis. The prostatic capsule, when intact, prevents many bacteria from penetrating prostatic tissue to a significant extent. However, in acute prostatitis the prostatic capsule often is disrupted such that any antibiotic to which a given organism is sensitive may be used to effect. Trimethoprim-sulfa antibiotics and fluoroquinolone antibiotics always penetrate the prostate well. Antibiotic therapy should be continued for 4-6 weeks, and culture performed one week and again one month after completion of antibiotic therapy. Concurrent treatment for benign prostatic hypertrophy, with castration or medical therapy with finasteride, may be beneficial.