Diagnosing Gastrointestinal Obstruction in Dogs
When an owner sees his dog swallow something large, sharp or otherwise potentially dangerous, he should take his pet to the veterinarian right away. Of course, many times, owners aren’t so lucky as to see the actual “event.” They may only notice that their dog is not acting normally, seems sick or lacks normal energy and appetite. When the dog has only a partial gastrointestinal obstruction, it may not show any outward symptoms of discomfort or distress. Still, most people are well enough in-tune with their pets that they eventually will recognize when they are not feeling right. By that time, a trip to the vet is in order. Frequently, the history that the veterinarian gets from the dog’s owner, and the results of the initial physical examination, are the most useful diagnostic tools. The vet will examine the dog’s belly. This may reveal gastrointestinal masses, intestinal intussusception (where part of the intestine gets stuck inside another part), abdominal pain or the presence of a lodged foreign object, depending on its size and where it is located. Strings, pieces of carpeting and other items called “linear foreign bodies” sometimes become wrapped around the back of a dog’s tongue and are swallowed, getting stuck in the esophagus between the tongue and stomach. These can be found when the veterinarian looks in the dog’s mouth, if the patient cooperates.
If the initial evaluation doesn’t identify a conclusive cause of the dog’s discomfort, the veterinarian probably will want to take a blood sample for routine blood work and a urine sample as well. The complete blood count can indicate whether the dog is anemic or fighting some form of infection, and the serum biochemistry profile and urinalysis can help the veterinarian assess other potential causes of the dog’s distress, such as disorders of the kidneys, liver, pancreas, thyroid gland or adrenal glands. The dog can also be evaluated for Addison’s disease, Cushing’s disease and diabetes. These simple testes usually give a very good snapshot of a dog’s overall health and are well worth the cost.
X-rays of the dog’s belly are one of the best ways to identify foreign objects that are stuck in its stomach or small intestine and they can also show blocked or distended loops of bowel, and possibly tumors or other abnormal growths. Radiographic contrast studies can also be helpful. This involves orally administering barium or some other radiopaque liquid to the dog and then taking a series of radiographs over time. The veterinarian will watch the liquid as it moves through the dog’s gastrointestinal tract. It will appear bright white on the mainly black and grey films. If something is lodged in the stomach or intestines, the contrast media will either stop moving or will squeeze around the object if it can. Contrast studies are extremely helpful to show delayed emptying of stomach contents through the stomach’s outlet portal (the “pylorus”), abnormal masses, constrictions of the intestines and lodged foreign bodies. Contrast studies also can pinpoint the precise location of the obstruction as the liquid slows or stops flowing through the intestine, pools and then “clogs up” backstream, much as the water in a river backs up and pools when a dam is built across it. Abdominal ultrasonography is another valuable diagnostic procedure that can be used to identify gastrointestinal obstructions.
Many veterinary clinics offer a more advanced procedure called gastroscopy or gastric endoscopy. Endoscopy is the direct visual examination of the inside of hollow organs or body cavities using a wand-like instrument with a camera at the end called an endoscope. They also come with various accessories, such as a suction tip, tubes and suction pumps, forceps for taking tissue biopsies or removing foreign bodies, and an electrode tip for cauterizing bleeding areas, if necessary. Gastroscopy involves sedating or anesthetizing the animal and inserting an endoscope tube through its mouth, down its esophagus and into its stomach. The veterinarian will be able to move the camera tip around, and rotate it, to look at all parts of the lining of the stomach. Many times, he will be able to pass the scope through the pylorus and visualize part of the upper small intestine. He can use the endoscopic accessories to take biopsy samples of areas that look abnormal, such as masses or other suspicious areas that are red, inflamed, ulcerated or bleeding. Finally, the veterinarian may be able to remove lodged objects using the endoscopic forceps, making open abdominal surgery unnecessary. Of course, this will depend on the nature, size and shape of the object, and where it is stuck.
Free fluid in the abdomen can be sampled through a process called abdominocentesis. This involves inserting a long sterile needle through the belly wall directly into the abdominal cavity, and drawing a sample of any fluid out through a syringe attached to that needle. There should not be fluid floating around freely in the belly. The veterinarian will look at the sample under a microscope to check for the presence of inflammatory cells, blood or infectious microorganisms such as bacteria. As a last resort, the vet can perform exploratory abdominal surgery to search for the cause of the obstruction and, hopefully, to remove it. This is called a laparotomy and must be done under full general anesthesia. If the dog has been diagnosed with gastric dilatation and volvulus (GDV; bloat; torsion) from X-rays, most veterinarians will immediately take that dog to surgery without further diagnostic tests, because surgery is usually the only way to resolve that life-threatening condition.
It can be difficult and frustrating to try and diagnose the reason for abdominal discomfort in dogs, especially without opening up the abdomen and taking a look around. In many cases, especially if a small foreign object is causing the dog’s symptoms, the cause may never be found. Because many types of GI obstruction can quickly become life-threatening, it is important for owners to be vigilant when their dogs are acting “off,” and take them to the veterinarian for assessment right away.