The Small Animal Internal Medicine Service offers a variety of advanced diagnostic procedures that are not routinely conducted by most veterinarians. These procedures may be completed by our internal medicine staff or through collaboration with other specialists in the hospital.
Some of these procedures include:
Endocrine disorders (hormonal disorders) are often difficult to identify accurately and manage. Most diagnostic tests for endocrine disease are blood tests. Our internal medicine specialists have years of training and expertise to best know which tests are likely to provide the most important information. They are also trained to correctly interpret the results of these tests in light of the entire, often confusing, clinical picture.
Some endocrine tests require the administration of a substance to either stimulate or suppress hormone production. Several days are required to obtain final results from most endocrine tests.
Rhinoscopy allows the veterinarian to visualize the inside of the nose and nasal passages. It is commonly used for animals with chronic nasal discharge, sneezing or nosebleeds. Sometimes we can identify fungal or parasitic infections, or we can see foreign materials lodged in the nose. It may also help guide us to the optimum location for biopsy when cancer of the nasal passages is suspected. Rhinoscopy requires general anesthesia and often follows imaging of the nose with a CT scan.
Bronchoscopy allows the veterinarian to examine the inside of the airways from the larynx at the back of the throat to the airways deep inside the lungs. It is often indicated to try to determine the cause of cough or difficult breathing. Although we cannot see all of the smaller airways, we can visualize airway collapse or stricture, deformity of the airways, foreign material within the airways, or excessive redness or mucus within the airways.
Perhaps most importantly, bronchoscopy can help us collect samples of fluid or tissue for further analysis under the microscope or through bacterial culture. Bronchoscopy always requires general anesthesia, and depending on the underlying disease may require recovery from anesthesia in an oxygen-rich environment under close supervision.
Upper GI endoscopy allows us to pass a scope with a camera through the mouth, down the esophagus or “food tube,” into the stomach and then on into the upper portion of the intestines. It is often indicated for animals with vomiting or diarrhea. We can visualize ulcers, tumors, strictures and other problems.
Multiple biopsies will be obtained during endoscopy, and these samples will require several days to analyze. Upper GI endoscopy is also commonly used to remove foreign objects, such as swallowed toys or fish hooks, without the need for more invasive surgery. Upper GI endoscopy requires general anesthesia. Sometimes it is combined with lower GI endoscopy.
Lower GI endoscopy allows us to pass a scope with a camera through the anus and up through the entire length of the colon (also called the large bowel or intestine). This procedure is typically indicated in animals with diarrhea or bloody stool, or in animals that have been straining to defecate.
Colonoscopy requires that the large bowel be free of any feces. Cleansing of the bowel takes a few days of preparation time before the actual procedure. Multiple biopsies will be obtained during endoscopy, and these samples will require several days to analyze. Lower GI endoscopy requires general anesthesia. Sometimes it is combined with upper GI endoscopy.
Cystoscopy allows us to pass a scope with a camera through portions of the reproductive and urinary tracts. It is often indicated in animals with recurrent urinary tract infections, urinary incontinence or bloody urine. Abnormal anatomy may be visualized, as may urinary stones or tumors of the urinary tract. Samples are sometimes obtained for biopsy. Cystoscopy requires general anesthesia.
Often a sample of joint fluid is required to identify joint disease that can cause lameness, fever, lethargy or reduced appetite. With the animal deeply sedated, the hair over a joint is clipped and the skin thoroughly cleaned. A small needle is then inserted into the joint, allowing us to retrieve a sample of joint fluid.
This fluid can be analyzed under the microscope for signs of inflammation or infection, or specialized tests such as bacterial culture can be performed. In animals with immune-mediated polyarthropathy, this test is repeated on a periodic basis to safely monitor disease while drug dosages are adjusted.
The bone marrow is the site where new blood cells are produced. In animals with disorders that cause too few cells in circulation, it may be necessary to examine the cell types found within the marrow. Bone marrow aspiration may also be used as a part of cancer screening or staging.
With the animal sedated, the area of the biopsy is numbed. The hair is clipped and the skin thoroughly cleaned. A special type of steel needle is inserted through the hard bone into the marrow (the pulpy material inside the hard bones). Some of this pulpy material is aspirated through the needle using a syringe. Sometimes, a piece of the marrow material is removed intact for biopsy. While the results of an aspirate are typically available the same day, the core biopsy may require several days to evaluate.
Ultrasound uses sound waves to create images of the structures inside the body; many people are familiar with such imaging studies when performed on pregnant women to examine the growing fetus. We often use this technology to examine the contents of the abdomen and sometimes use it to look at other parts of the body as well. The ultrasound images are complementary to conventional radiographs (X-rays). In fact, it is routine to obtain radiographs prior to ultrasound exam so important findings are less likely to be missed.
In order for the sound waves to create a good image, the hair over the area is usually clipped, and a gel substance is placed on the skin. The procedure itself is not painful and is extremely safe, and it can often be completed with the animal awake. Sometimes sedation is required for pets that are anxious or squirmy. Although the ultrasound examination is not invasive, it is often used to help guide us to a specific site to collect biopsies or needle aspirates from diseased tissues. Sedation or even anesthesia may be required to make sample collection as safe as possible.
Plain film radiographs, or X-rays, allow us to visualize the inside of the body. These images do a great job showing bone and can also be used to examine soft tissues such as the lungs, liver and kidneys. Because radiographs produce a two-dimensional picture, it is necessary to obtain at least two separate views so overlapping structures can be seen well. Although radiographs are useful, they have distinct limitations. For this reason, other imaging modalities such as ultrasound are often used along with radiographs.
Fluoroscopy can be thought of as “moving picture X-rays.” It allows us to visualize dynamic processes, such as collapse of the trachea during a dog’s cough, or disorders of swallowing. Because this test requires the animal to move (such as coughing or eating), it is not usually sedated or anesthetized.
Computed tomography uses a similar technique as is used in plain radiography (X-rays) to create a more detailed picture of the inside of the body. As the animal passes through the CT scanning machine, a series of cross-sectional images are generated, much like slices through a loaf of bread.
Although plain film radiographs can obscure anatomy because all the tissues lay on top of each other, with a CT scan the images may be manipulated in different planes, allowing tissues to stand out from the background and for the examiner to gain a much better appreciation for anatomical relationships. CT scans can even be used to create three-dimensional images. In most cases, anesthesia or sedation is required to obtain CT images.
PET scans use a small amount of radioactive material and a special camera to identify abnormal tissues, including infected or cancerous tissue. Most often, the radioactive material is linked to sugar, and the sugar is taken up by active tissues. PET scan is most useful when it is combined with CT imaging to both identify the abnormally active tissue and see what that tissue looks like anatomically. Because active muscle will take up the sugar molecule, animals must be kept very quiet for a period of time before the test. Typically, they are kept sedated first and then fully anesthetized for the actual test.
We are fortunate to have a fully accredited microbiology laboratory on the premises. This means that when we suspect a bacterial infection, samples of fluids or tissues can be processed for culture immediately. When samples for culture must be shipped through the mail, there will be some loss of growth potential, possibly resulting in a false-negative test.
Culture allows pathogenic bacteria to be grown in an incubator and then identified as to species. Further, these bacteria can be tested to see what type of antibiotics are most likely to be useful in eradication of infection.
Often, we need to examine cells under a microscope to help make a diagnosis. There are several ways to do so, including taking a standard surgical biopsy or a needle biopsy. To collect cells for examination via a needle, there are two ways: fine needle aspiration (FNA) or needle biopsy.
Fine needle aspiration is a fairly simple technique in which a needle of about the same size as those used to administer vaccines is introduced through the skin and into a tissue such as a lymph node or a mass. In some cases, a syringe is also attached and used to “aspirate” or draw up cells, while in other cases the needle is simply moved inside of the tissue. The needle is then removed, the very small sample is expelled onto a glass slide and the slide is stained for microscopic examination.
The advantage of this technique is that it is quick, simple and usually safe. The disadvantage is that we examine only a few hundred cells out of millions, so we may not get a representative sample. In most cases, results of this test are available the same day it is performed.
A true needle biopsy uses a much larger needle to obtain a small core piece of tissue. That tissue is “fixed” in formalin, processed for examination and then examined microscopically. This type of biopsy gives a larger specimen and preserves the architecture of the tissue, but it requires several days to get results and often carries more risk.
Depending on the tissue being biopsied, FNA usually does not require anesthesia. Needle biopsy may require sedation or anesthesia.