Gastrointestinal Endoscopy in Dogs and Cats
March 21, 2013
This procedure may be recommended by your veterinarian as part of an investigation into causes of your pet’s illness signs, which may include: vomiting, diarrhea, weight loss, abdominal pain or loss of appetite. Sometimes endoscopy is also used to investigate a specific finding noted on another testing modality, such as x-rays or ultrasound (evaluation of a mass, foreign body in the stomach, possible stomach ulcer, etc.). The esophagus can also be evaluated with endoscopy (if a foreign body, mass, stricture/narrowing or inflammation is suspected). This procedure is typically performed by a board certified internal medicine specialist.
What is an endoscope and how is it used?
An endoscope is a flexible tube with a video camera attachment that is inserted either into the stomach and duodenum (first part of the small intestines) through the mouth, or the colon via the rectum. It permits inspection of the inside of these hollow structures. If the stomach/duodenum is being examined, the esophagus is also inspected as the endoscope is being passed into the stomach.
What types of disease are diagnosed with an endoscopic examination?
The endoscope allows full color viewing of the aforementioned organs using video. The examiner can identify abnormalities such as inflammation, ulceration, abnormal swelling/masses or areas of scarring or stricture (abnormal narrowing). If a foreign body such as a bone, stick, rock, toy, coin, or hairball is seen, it can usually be seen and retrieved. Photos and video can be recorded for future reference.
Can viewing an abnormal area give the diagnosis?
While seeing an abnormal lesion or suspicious area gives us valuable information, it is usually necessary to biopsy the area in order to reach a diagnosis. The endoscope has a tiny channel through which a biopsy instrument can be passed. Precise biopsy samples, which consist of tiny “bites” or pieces of tissue cut from the surface tissue or lining of the organ by the biopsy instrument. These samples, called “pinch biopsies” are then submitted to a veterinary pathologist for microscopic evaluation. They are usually about the size of the head of a pin.
What happens if you don’t see any abnormal areas?
Many diseases cause changes that can only be detected by histopathology, or a microscopic inspection of the tissues. Therefore, even if the organ or tissues appear normal, biopsies are taken. In most cases, the biopsies will be very helpful in determining if disease present.
What if the problem is in the small intestine?
In most patients, it is possible to pass the endoscope through the pylorus (a valve at the exit from the stomach) into the upper part of the duodenum. This depends on the size of the pet (may be challenging in extremely small or extremely large animals). Unfortunately, the majority of the small intestine is inaccessible to the endoscope. In many cases, the disease process is thought to be diffuse, meaning that it affects all of the small intestine in a uniform fashion, and the biopsies taken from the duodenum are representative of the small intestine as a whole. In some circumstances, endoscopy may not be the best test for the patient if the disease is thought to be localized to parts of the small intestine that cannot be reached with the endoscope.
Can cancer be diagnosed with endoscopy?
In many cases, your veterinarian can diagnose cancer of the gastrointestinal tract using the endoscope. However, some tumors do not affect the mucosa or inner lining/surface of the stomach, duodenum or colon. Since the biopsy procedure only samples the mucosa, it is possible to miss detecting a tumor that is present only in the deeper layers of the bowel. In these unusual cases, the surface biopsies will be normal but the pet continues to experience clinical signs. In order to reach a diagnosis in these cases, full-thickness biopsies obtained through an exploratory surgery or other diagnostic tests may be necessary.
What steps need to be taken to prepare for endoscopy?
It is vital that the inspected organs be empty of all food, water and fecal matter. If the stomach and duodenum are to be examined, withholding food for twelve hours is generally sufficient. If the colon is to be examined, the pet is generally hospitalized for twelve to eighteen hours before the procedure for administration of oral medication and enemas to remove stool from the colon. The pet is also fasted during that time period so new fecal material does not form.
Is general anesthesia required?
Yes. It is impossible to pass an endoscope safely into a conscious animal’s gastrointestinal tract. In most cases, a short-acting anesthetic is used, and the pet can usually go home the same day as the procedure.
When will I know the results?
Since the organs are viewed in real time, the result of what is seen is known immediately. However, the final diagnosis usually depends on the results of the pathologist’s study of the biopsies. This may take up to a week, depending on the individual circumstances.
– Tabitha Hutton, DVM, MTR, DACVIM (SAIM)
Adapted from Lifelearn, written by Ernest Ward, DVM
© Copyright 2009 Lifelearn Inc. Used and/or modified with permission under license.