Gazette Vet: The Open Diagnosis


By John Andersen, DVM

After graduating from veterinary school at Virginia Tech, I moved to Raleigh, NC, for a year to work at the NC State University Veterinary Teaching Hospital as an intern. This was a year I would work slave hours for peanuts, but would gain valuable experience to better my performance as a veterinarian in the real world.

Working as a “small animal” intern (dogs and cats…) meant rotating through 2-3 week blocks on different specialty services throughout the year—internal medicine, surgery, cardiology, oncology, ophthalmology. Being engrossed in each of these disciplines multiple times throughout my year taught me a ton and gave me a humble start to my career.

One of the most striking lessons I learned, in particular on the internal medicine rotations I was on, was how infrequently patients actually leave with a definitive diagnosis.

Coming to a specialty referral center like the NC State veterinary school were all of the tough cases—sicknesses that either could not be diagnosed by their primary veterinarian, or were simply not responding to treatment. By my rough estimate, I felt as though we were only able to give the pet owners a definitive diagnosis about 50 percent of the time.

Let me clarify. By definitive diagnosis, I mean being able to tell the owners exactly what was wrong with their pet and why. For example, if a patient was brought in for weight loss and excessive drinking and urination, and the blood work revealed high blood sugar and no other abnormalities, I would have no problem making a definitive diagnosis of diabetes mellitus.

However many cases are not that easy, and determining what to do and how far to take the case is a complex decision with many factors. Let’s take a common example:

“Jessie” is a 14-year-old cat who has been losing weight for the past three months. The cat is acting completely normal, but isn’t eating as much as she used to. On exam, it is clear that Jessie is losing some core body weight, as she has a palpable bony spine and seems weak in her rear legs.

So we talk to the owner about running some blood work, which all comes back normal.  “Dang it!” I usually say, because gone are the easy answers that I can usually diagnose right from the lab work.

So what now? “I just paid you all that money for blood work and you still can’t tell me what’s wrong with her?!” Most people are quite understanding, but yes, you did just spend all that money on blood work and I still have no idea why your cat is sick! How about we spend some more money on tests that also are not guaranteed to find a diagnosis?  

These are tough cases in which we are balancing the desire to find and fix a problem with the real life issue that the owners are paying 100 percent of the bill out of their pocket.

So, let’s say the lab work is all normal. I still haven’t had a pet talk to me yet. Now it’s time to put on the old “critical thinking” hat.

Critical thinking is such an important skill in practicing medicine, and I would argue, in any job with problems. Many times, the evidence, the manuals, and the experts may let us down in our quest to solve problems. There may come a time when we are getting no good information, or worse yet, conflicting information, and we need to make a decision. Back to Jessie.

I make the case to Jessie’s owners that the blood work is normal, so we need to do some further testing. I tell her that I can rule out several possible diseases—i.e., Jessie does not have kidney disease, diabetes, or thyroid disease. “They why is she losing so much weight?”  I just don’t know.

So I convince Jessie’s mom that we should do an abdominal ultrasound and a chest X-ray.  “What are you looking for” Jessie’s mom surely would ask. Cancer. Bad stuff. Maybe something treatable?  

So we do the rays and ultrasound. Normal. Nothing. Ugh.

We have depleted the “pet’s bank account,” and the more treatable diseases we seem to be ruling out, the more the very real question comes up—how much more testing should we do?

On one hand, we can keep going. I might suspect intestinal cancer or inflammatory bowel disease. Usually a gut biopsy will tell me that. So, Mrs. Jones, would you like me to cut open your poor old 14-year-old cat to diagnose what is wrong with her, even though it is likely cancer or another terminal process? But how do I know for sure?

These are times when I have a very open discussion with owners about the limits of our testing and ultimately, what diseases she doesn’t have and what diseases she could have.

In Jessie’s case, I feel very confident that she either has intestinal cancer or inflammatory bowel disease. Years of experience have taught me that both of these diseases are quite common in older cats, and although the specialist recommends opening her up and getting a gut biopsy, I think that is a bit invasive!

These diseases often come to the point of “let’s treat the treatable.” Yep, Jessie could have cancer, in which case we would not likely be able to save her or improve her quality of life very much. However, maybe she has inflammatory bowel disease, which is actually a very manageable disease! Instead of cutting Jessie open and taking painful biopsies, perhaps a more reasonable approach is to start her on steroids that can effectively manage IBD.

Mrs. Jones likes that approach for Jessie, and what do you know, two days later Jessie is eating better than she has in months! I tell Mrs. Jones how happy we are that she is finally feeling better, but then I have to break some news to her—sometimes cats with cancer feel good temporarily after steroids.

“So what you’re telling me is that you still don’t know what’s wrong with her?”

Yep, I still don’t know what’s wrong with her, but I’m so glad we have made her better!

Cases like Jessie’s are a daily occurrence in the world of vet medicine, but, fortunately, because of the power of critical thinking, we are often able to find an answer, or at least a way to make them feel better.


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