From The Case Files: What The Prostate Exam Revealed

Dr. Jonathan Mitelman, DVM, and Barbara Kelly

Luca, a neutered eight-year-old Shetland Sheepdog, was having difficulty with his bowel movements.

His new dog walker noticed that Luca was straining, and squatting for extended periods without passing stool. In addition, the dog's first-morning urination appeared normal but was often followed by repeated attempts to "go,” with only dribbles as a result.

When hearing this from the dog walker, Luca's owner was surprised as the sheltie had a good appetite, was acting normally at home, with no sign of malaise. He checked with the previous dog walker, who, on reflection, confirmed Luca had been doing this for awhile.

It hadn't registered that there was a problem.

Luca's owner brought him to VETSToronto at the Kingston Road Animal Hospital, where senior veterinarian Dr. Morris Samson did the first examination and assessment. Obtaining a thorough history from the owners, he learned that Luca's painful defecation and periods of straining during urination could be traced back one to two months.

A digital rectal exam, essential to every physical examination, was performed and what Dr. Samson found was startling.

There was a large, palpable bilobed mass consistent with an enlarged prostate. 

This is most unusual in a dog that was neutered as a puppy.

Dr. Jag Verma, one of the hospital's on-site emergency care veterinarians, was called in for a consultation. He concurred with Dr. Samson's findings. Was this a prostatic tumor, prostatic hyperplasia, a prostatic cyst, or a prostatic infection?

A ball shaped urinary bladder 
just left of centre, a tubular 
descending colon running above 
the bladder from left to right 
through the pelvic canal. 
The bone of the pelvic floor 
is not smooth, note the flare. 
The prostate is not visible here.

The doctors knew further investigation and diagnostics were necessary.

Radiographs were taken and revealed an abnormal soft tissue mass in the pelvic canal, at the entrance to the pelvic inlet.

Most alarming was that the bone on the floor of the pelvic canal was not as smooth as it should be. It was raised and rough, indicating reactive bone.

It was necessary to obtain samples for urinalysis and cytology, preferably in a non-invasive manner. Dr. Samson had difficulty passing the urinary catheter beyond the level of the prostatic urethra, but he was able to acquire both urine and a prostatic wash for analysis.

Unexpectedly, there was a gush of blood from the penis following the removal of the catheter. Blood was also visible in the urine sample.

Dr. Samson spoke with Luca's owner, sensitizing him to the likelihood of cancer. As Luca was comfortable, his owner decided to take him home with the prescribed antibiotics and await the test results.

The cytology results were ambiguous, revealing cells that represented inflammation but not abnormal enough to be cancer. 

More conclusive evidence was needed and an on-site ultrasound with tissue biopsy done by Dr. Jonathan Mitelman at VETSToronto was recommended.

After doing another physical exam of Luca, Dr. Mitelman performed the ultrasound. His findings revealed the following areas of concern:

1. The prostate was an enlarged irregular mass, showing mineralized tissue within.
   
2. The bladder contained bits of dense material consistent with tiny stones and also roughened polypoid mucosa that could be inflamed tissue or a developing tumor.
   
3. Nodules were found throughout the liver tissue, the pattern suggesting something sinister. They could represent Hyperplastic bile ducts, a benign process. Or it could be neoplasia which was spread through the bloodstream from a primary site, in all likelihood the prostate being the culprit.
   
4. Early changes in his gallbladder consistent with a mucocele (inflammation of the gallbladder with mucus build up in its walls).

A small accumulation of stones (white, centre) 
collected in the urinary bladder

A 2.2 cm nodule in his liver, one of many nodules of various sizes found.

Examining his prostate using a rectal ultrasound probe, 
the prostate is seen spilling over the pelvic inlet into the abdominal cavity. 
Note the many white irregularities (representing mineralization) 
throughout the tissue.

Prostate of a nine year old dachshund (Billy) 
neutered one year earlier for comparison. His prostate has shrunken down 
in size to the current dimensions, 2.5 x 1.3 cm. 
Note the homogenous appearance of the organ.

Dr. Mitelman was able to insert the ultrasound probe into Luca per rectum, thus visualizing the prostate. He then passed a catheter through to the prostatic urethra intending to collect cytology. Although gently advanced, the catheter penetrated through the friable and weak urethral wall and into the prostatic parenchyma. As a result cores of solid tissue samples were collected from a urinary catheter.

This was the first time Dr. Mitelman collected a tissue sample this way as usually a TruCut biopsy needle would be used to collect solid samples of prostatic tissue.

The pathology results confirmed what all of the doctors had suspected. Sadly Luca had prostatic carcinoma. 

This type of cancer has the properties of rapid local growth and invasion into nearby tissue (bladder, bone), spread to local draining lymph nodes and to bone, liver, and lungs. In dogs, the behavior of prostatic cancer results in rapid progress and a poor outcome; in humans, the progress and prognosis are much different.

Dr. Mitelman consulted with oncologist Dr. Wayne Shapiro who offered the following treatment options.

The first would be surgical removal of the prostate to minimize the volume of cancerous tissue. The second would be radiation, the third chemotherapy. The fourth would be a combination of the previous three.

Risks of surgery are many, the side effects of the treatments might be harsh and make the dog feel sick and uncomfortable. Even with these treatments the prognosis is poor, often only buying a matter of a few months. Dr. Mitelman spoke with Luca's owners and offered a referral to a local oncologist. The owners decided that conservative treatment and palliative care would be best for the dog and the family.

With the diagnosis of prostatic carcinoma confirmed by the biopsy and the inevitability of a shortened life, Luca's owners opted not to pursue further investigation of the bladder or liver.

Luca’s pain originated from the pressure of the stool moving through the colon over the inflamed prostate. 

He was taken home with NSAIDS (which have anti-angiogenic properties), anti-oxidants, opiate painkillers when needed, low residue diet and lots of TLC.

Three months after diagnosis, Luca's owner says the dog has good and bad days. They are managing the pain and Luca maintains a good quality of life. They are taking the process one step at a time.

Lessons Learned

1. Neutered and un-neutered male dogs develop prostatic cancer at the same rate. It might seem otherwise as intact males present more reasons to go looking.
2. A veterinarian should always do a digital rectal exam to palpate the prostate and anal sac tissue. If you feel the prostate in a dog that was neutered at a young age, you may be dealing with cancer.
3. It is important to know the urination and defecation habits of your pet. A difficulty with either, straining, pain, dribbling etc. should be reported to your veterinarian and investigated.
4. When given a diagnosis such as cancer, it is wise to explore all options and ask for consultations and/or referrals to specialists. Knowing all available treatment options helps you make a decision that is best for your dog and allows you comfort with your choices.
5.  Perception of pain is in the eye of the beholder. Let your pet be the guide.

More case files: 
From A Swelling To Necrosis In Days