Is It Cancer? Never Assume

October 10, 2012

Many patients never get the surgery they need or are euthanized because veterinarians or owners assume that a mass is cancerous.

It’s not uncommon for a referring veterinarian to call me to perform surgery on a patient with a “splenic tumor.”  I tend to call it a “splenic mass” until proven otherwise by my pathologist. Understandably, clients often don't want to put their pet through surgery if it's likely to be cancer. But that’s obviously a decision based on their family vet’s assumption.

The truth is, it sometimes doesn't really matter if a mass is benign or cancerous. A benign mass can cause some very annoying signs depending on where it is located: a large mass in the rectum preventing a dog from defecating; a large cervical mass pushing on the trachea and causing severe dyspnea; a large axillary mass preventing a dog from using the leg normally.

Benign intestinal mass in a 9-year-old Golden (jejunal leiomyoma).

These masses might have been benign, but they still caused some significant signs that dramatically affected the pet's quality of life.

We recently did surgery on three patients; all the names used here have been changed. "Everybody" just knew they had cancer. But their owners just loved their pet too much and couldn't put them to sleep without at least the benefit of surgery.

Max is a 13-year-old male Sheltie. X-rays revealed a large splenic mass. Based on the way it looked on ultrasound, we believed the mass to be malignant. Taking an ultrasound[1]-guided biopsy of the spleen is possible, but it can be risky; the mass can rupture and the biopsy can cause "seeding."

Despite the odds, John, Max's owner, was interested in surgery, which was performed the next day. The mass was the size of a cantaloupe (in a Sheltie!), and looked really ugly–i.e. vet code for "Man, this oughta be cancer." Max recovered uneventfully.

One week later, the biopsy came back as … benign! The mass was a myelolipoma. Max is now expected to have a normal quality of life and a normal life expectancy.

Jake is a 12-year-old male cocker who had difficulty urinating. Ultrasound showed a large mass in his bladder. Bladder masses are much more often cancerous than benign. Linda, the owner, elected to have the mass excised anyway.

We took Jake to surgery a few days later and removed about one third of his bladder.  One week later, the biopsy came back as … benign! The mass was a leiomyoma. Jake should have a normal life expectancy and a normal quality of life.

Praline, a 9-year-old Labrador, had a pretty big mass under the tail. She was referred for a tail amputation, because the mass was thought to be cancer. For some reason, call it a gut feeling, I wasn't too thrilled to do that, and of course neither was the owner.  So we decided to remove the mass only. 

Upon section postoperatively, the mass appeared dark, so I was concerned it could be a malignant melanoma. One week later, results came back: the mass was benign!  It was a cyst in a sweat gland.  Again, this mass will not affect the patient's life span, and Praline got to keep her tail.

The list could go on.

The moral of the story: Never assume.

I am perfectly aware that the diagnosis could just as easily be bad. In fact, it was supposed to be, based on experience and statistics. But here are three older dogs, some would say in the last part of their lives.

They all were statistically "supposed" to have cancer. But these loving owners, willing to provide the best possible care for their pet, were not going to give up without a fight. In fact, out of countless patients who did have cancer, I don't remember a pet owner ever regretting choosing surgery over euthanasia, no matter how much extra time we bought.

The goals of tumor removal are to obtain a diagnosis, improve the patient's quality of life (e. g. being able to urinate or defecate or breathe), increase life span, and decrease future risks (e.g. by preventing a hemoabdomen secondary to rupture of a splenic mass).

Over the years, I have become much more cautious when a pet owner asks me whether I think a tumor is benign or malignant. I simply say, "I don't have microscopic vision," and that I just don't know.

Some clients hate this answer, but I would rather say that than give a client unnecessarily poor odds or false hopes.

In the case of Max*, Jake* and Praline*, three extremely dedicated owners were rewarded with an excellent diagnosis, an outstanding prognosis, and hopefully many more happy years with their dogs.

Dr. Zeltzman[2] is a mobile, board-certified surgeon in Allentown, Pa. He is the co-author of “Walk a Hound, Lose a Pound.”


  1. ultrasound: /January-2013/Ultrasound-A-Go-to-Diagnostic-Tool/
  2. Zeltzman:

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