— By Dr. Perry Jameson
Part of the reason I (Perry Jameson) chose to become a veterinary internal medicine specialist was that each patient is a mystery. Most of my patients are sent to me to figure out why they are sick or why their blood work is abnormal.
The investigation begins with a review of what was done by their family veterinarian. Next I get a thorough history from the parents followed by a physical examination. I may then recommend certain blood and urine tests.
Ultimately, for many patients, some form of imaging is required to look deeper. This may include X-rays, ultrasound, CT scan and MRI. These tests let me look inside of the patient for changes at a visible level. Despite all the advances I have seen in what is available to image my patients, they still do not tell me what is going on at a cellular level.
X-rays of the lungs may reveal an area of inflammation. What they cannot tell me is this inflammation from bacterial pneumonia or asthma. These diseases are treated differently so it is vital that I know which one my patient has to plan therapy. Quick sedation and collection of the mucous from down in the airway allows me to get a sample to assess microscopically.
These samples are sent to a veterinary pathologist. These are veterinarians who have received advanced training in assessing disease at a microscopic level. They no longer see patients but instead help the veterinarians that do, such as me, make a diagnosis by sitting in front of their microscopes all day.
Despite all of their training and experience, their ability to give me a diagnosis is still limited by the samples I submit to them. The larger the sample the more likely they can give me an answer. The problem there is the larger the sample, the more my patient has to go through to obtain it.
Stella was a 9-year-old mixed-breed dog who came to me because she had been vomiting for several weeks and not eating well. Her blood tests revealed her liver values to be elevated. I performed an ultrasound of her abdomen and found multiple lymph nodes internally to be enlarged. These lymph nodes would be enlarged for two reasons: inflammation or cancer. Via ultrasound, however, I could not tell the difference. Her liver looked normal, but for her blood tests to be abnormal, something had to be going on at a microscopic level.
I had to get a sample of her lymph nodes and liver for the pathologist to assess under the microscope to determine what was wrong with Stella and to be able to treat her effectively. The two main ways for me to get this sample was by performing a fine-needle aspirate or exploratory surgery.
A fine-needle aspirate is where I use the ultrasound to guide a small needle into one of the lymph nodes and the liver to extract a sample. The nice thing about this technique is the risk and discomfort for my patient is low. The needle is smaller than that used for drawing blood so in many dogs and cats, this can be done without sedation. For most pets, this can be done as an outpatient allowing them to go home while we await the results.
The drawback of this sampling technique is the samples are small. Sometimes I do not get enough cells for the pathologist to give me an answer. So I can never guarantee success when doing a fine-needle aspirate.
The other option is to obtain biopsies surgically. Here, we can get multiple large pieces for the pathologists. Whole tumors and lymph nodes can be submitted. It is rare with these large pieces that they cannot provide me with a definitive answer.
The drawback with surgical biopsies is that the patient must undergo surgery. They have to be under general anesthesia and are usually hospitalized for at least 24 hours. They are often uncomfortable for several days afterward.
For Stella, I had to decide between the two procedures.
Mom and Dad and I elected to try the fine-needle aspirate first. If surgery would have provided some form of therapy, such as removing a solitary tumor, they probably would have elected that first.
After 24 hours of waiting, the pathologist called and she was able to give us an answer. Stella has lymphoma in her lymph nodes and liver. Not the news we wanted to hear, but at least got our answer with little discomfort for her.
Dr. Henri Bianucci and Dr. Perry Jameson are with Veterinary Specialty Care LLC. Send questions to petdocs@postandcourier.com.
