At the Animal Clinic at Thorndale, we are fortunate to have a number a board certified veterinary specialists close by. At times, the diagnosis of an ongoing digestive problem your cat is experiencing is either beyond our capabilities or can be more easily accomplished with less trauma to your cat by a technique not at our disposal. One of these techniques is endoscopy. In the past, in order to examine and biopsy the digestive tract, we performed an abdominal exploratory surgery in our hospital. While we still do exploratory surgeries, (mostly for other reasons), we also think owners need to be aware that a bowel biopsy can be obtained without a major abdominal incision. Generally, prior to an endoscopic examination of your cat, we will first refer you to a board certified internal medicine specialist. There may be other testing or therapies to try prior to scheduling an endoscopic examination.
Endoscopy of the Gastrointestinal Tract
If your cat is to be scheduled for an endoscopic examination of the gastrointestinal tract, here is some useful information. The gastrointestinal tract is composed of the stomach, small intestine, and large intestine (or colon). The purpose of this endoscopic procedure is to visually inspect the lining of the gastrointestinal tract for the presence of obvious abnormalities and to obtain a small amount of tissue for microscopic study.
An endoscope is a flexible tube which contains fiberoptics. This technology allows study of the gastrointestinal tract and offers the potential for diagnosis of many diseases without exploratory surgery. Therefore, endoscopy is less invasive and less traumatic to your pet. The limitation is the “reach” of the endoscopic tube. Only the inside surfaces of the accessible portions of the digestive tract can be examined. Other internal organs cannot be seen.
To examine the upper gastrointestinal tract, the endoscope is inserted into the mouth to examine the esophagus, stomach and small intestine. After reaching the stomach, the scope is passed through the valve at the lower end of the stomach (pylorus) and into a short segment of the small intestine (duodenum). Successful entry into the duodenum depends upon the size of the cat and the size of the endoscope. Even when the duodenum can be examined and a biopsy obtained, most of the small intestine is not accessible to endoscopy. Some diseases of the small intestine require additional tests to complete the workup. In many cases, the colon is also examined and one or more biopsies will be taken.
Since the organs are viewed in full color and in “real time,” some results are known immediately. For example, the veterinarian will be able to look for areas of inflammation, ulceration, and any abnormal structures, such as a mass or stricture. Foreign bodies (bones, toys, rock, coins, hair balls, etc.) may also be seen and, in some cases, removed. To complete the study, results of microscopic examination of one or more pinch biopsies must be obtained. Time involved for these results will vary from a day to a week, depending on the location of the pathologist and the need for any special tests on the tissue.
To obtain the biopsies, the endoscope has a tiny channel, or port, through which a biopsy instrument can be passed. Small biopsies can be taken of specific areas which may appear abnormal. Even if the tissue appears normal, several biopsies will still be taken because some diseases are diagnosed only with microscopic study of tissue. Because the amount of tissue sampled is very small, complications from obtaining a biopsy are very uncommon.
It is vital that the inspected organs be empty of food and water prior to the study. If the stomach is to be examined, withholding food and water for 12-18 hours is generally sufficient. If the colon is to be examined, then oral medication will begin 12-18 hours before the procedure to remove fecal material from the entire intestinal tract. Fasting for 12-18 hours is also vital so 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.
Endoscopy for cats has two primary disadvantages. You should be aware of these prior to the procedure.
- Superficial biopsy. One shortcoming of endoscopy is that it only samples the surface layer (mucosa) of the gastrointestinal tract. Some tumors do not involve this superficial layer and are located deeper in the wall of the stomach or intestine. In this case, endoscopic biopsy will not achieve a diagnosis
- General anesthesia. Passing an endoscope into an animal’s stomach or colon is not possible in an awake patient. Furthermore, the patient’s cooperation is vital since the equipment that is used costs several thousand dollars and is quite fragile. Even for endoscopy of the colon, a short-acting anesthesia is required. However, the anesthetics available today are very safe.