The purpose of endoscopic examination is to help your veterinarian make a diagnosis of the disease that has been causing your pet's clinical signs of vomiting, diarrhea, weight loss, abdominal pain or swelling, or loss of appetite.
What is an endoscope and how is it used?
An endoscope is a flexible tube with a viewing port and/or a video camera attachment that is inserted either into the stomach through the mouth or the colon via the rectum. It permits inspection of the inside of these hollow structures. If the stomach is being examined, the esophagus (the tube connecting the mouth and stomach) can be inspected as the endoscope is passed into the stomach.
What diseases are diagnosed with an endoscopic examination?
The endoscope provides a full-color view of the esophagus, stomach, and upper part of the small intestine or colon. The examiner can identify abnormalities such as inflammation, abnormal swelling, masses, and areas of scarring or stricture (abnormal narrowing). If a foreign body is present, it can usually be seen and retrieved (e.g., a bone, stick, rock, toy, coin, or fabric).
Can viewing an abnormal area give the diagnosis?
While seeing an abnormal lesion or suspicious area gives your veterinarian valuable information, it is usually necessary to biopsy the area (take a tissue sample) to reach a diagnosis. The endoscope has a tiny channel through which a biopsy instrument can be passed. Precise biopsy samples can be taken of any abnormal areas. These samples consist of tiny pieces of tissue cut from the lining of the organ by the biopsy instrument. The tissue samples are then submitted to a veterinary pathologist for microscopic evaluation.
What happens if you don't see any abnormal areas?
Many diseases cause changes that can only be detected by histopathology, or inspection of the tissue under a microscope. Therefore, even if the organ or tissues appear normal, biopsies will still be taken. In many cases, a biopsy of the stomach of a vomiting dog or the colon of a dog with diarrhea will help determine if disease is present.
What if the problem is in the small intestine?
In many dogs, it is possible to pass the endoscope through the pylorus (a valve at the exit from the stomach) and into a short segment of the upper duodenum (upper part of the small intestine). How far into the small intestine the endoscope can be safely passed depends on the size of the dog and the size of the endoscope. Unfortunately, most of the small intestine is inaccessible to the endoscope, so other diagnostic procedures are usually required to diagnose many types of small intestinal disease.
Can cancer be diagnosed with endoscopy?
In many cases, your veterinarian can diagnose cancer of the gastrointestinal tract using an endoscope. However, some tumors do not affect the inner surface of the stomach or colon. Since the biopsy procedure only samples the inner surface, it is possible to miss a tumor that involves only the deeper (outer) layers of the intestinal tract. In these unusual cases, the biopsy results are normal, yet the dog continues to experience clinical signs. If the cancer occurs in a portion of the intestinal tract that cannot be reached by endoscopy, it may remain undetected.
To reach a diagnosis in these cases, additional tests may be required. This could include full-thickness biopsies obtained through an exploratory surgery (exploratory laparotomy) or non-invasive tests such as an MRI (magnetic resonance imaging) or CT (computed tomography) scan.
How do I prepare my dog for endoscopy?
It is vital that the stomach and intestinal tract be empty of all food, water, and fecal matter before an endoscopic evaluation. If the stomach is being examined, withholding food and water (fasting) for 12 hours is generally sufficient.
If the colon is to be examined, oral medication is begun 12 to 18 hours before the procedure to remove fecal material from the intestinal tract. Fasting for 12 to 18 hours is also necessary so that new fecal material does not form. On the morning of the procedure, one or more enemas are given to remove any remaining stool from the lower intestinal tract.
Is general anesthesia required?
Yes. It is impossible to safely pass an endoscope into a conscious dog's stomach or colon. Most dogs require only a short-acting anesthesia and can go home shortly after completion of the procedure.
When will I know the results?
The organs are viewed in real time, so those visual results are known immediately. However, the final diagnosis usually depends on the results of the pathologist's study of the biopsies. This step may take up to several weeks, depending on circumstances.
