VET CHECK: GASTROINTESTINAL OBSTRUCTIONS IN DOGS

While the intelligence of dogs in so many areas is highly regarded and proven a million times over, their ability to harm themselves by eating the most ridiculous, tasteless, large, and completely indigestible items can only leave a person shaking their head and wondering, “What was he thinking?” Rocks, wood, corn cobs, bones, all sorts of toys, garbage, baling twine, desiccated rodent cadavers, ribbon, collars, harnesses, truck wiring, chunks of glass and foam, other detritus from late night dog drops at highway rest areas—if a dog can swallow it, it can become a gastrointestinal foreign body. I have long since given up the endless cry of “why, why why?” Dogs eat stupid things and what is most amazing about it is just how often they can magically vomit or defecate said solid object with no ill effects. The problems arise when they become stuck in transit. In sled dogs, intestinal obstructions from rocks are a very common problem, with collar and harness ingestion seen often as well. “Linear” foreign bodies, such as baling twine, or even a nylon webbing collar eaten months ago that has begun to unravel while sitting in the stomach, pose a much greater risk to the patient. If one end of the linear foreign body becomes trapped in the stomach, and the “tail” trails down in to the intestine, the muscular contractions of the intestine as it attempts to pull the “tail” along can create a sawing effect on the wall of the intestine. This can in turn lead to a perforation. If the intestine is perforated, the bacteria-ridden contents of the intestine can leak out into the abdominal cavity, creating a condition called peritonitis. This is a life-threatening disease that has a much poorer prognosis for survival. Occasionally, even blunt objects (a popsicle stick, for example) can perforate the bowel and create peritonitis as well. Large, blunt foreign bodies are notorious for sitting in the stomach for very long periods of time, causing no symptoms whatsoever until they finally exit into the intestine. If you are lucky, the dog will vomit these objects up spontaneously. For instance, when you catch a dog in the act of eating a foreign body, inducing vomiting may be helpful. DO NOT induce vomiting for very sharp objects or very large objects. If they damage the esophagus as they are brought back up, the dog’s prognosis is much poorer than it would be with surgical or endoscopic removal. How large is too large depends on the size of the dog and the size and shape of the object; it is a worth a call to your veterinarian to ask. For soft, blunt objects (i.e. he ate a collar or harness within the last 3 or 4 hours), you may give a tablespoon (15 cc) of fresh hydrogen peroxide to induce vomiting. This can be repeated again in 10 minutes if he fails to vomit on the first dose. If more than 4 hours have passed since he ingested the object, inducing vomiting is probably not a good idea, call your veterinarian. If the consumed object is sharp, call your veterinarian. Sometimes small sharp pieces can be safely passed by administering a bulking agent that protects the sharp edge, but you should only do this on the advice of your veterinarian. Things like tacks can be passed by feeding the dog 4 or 5 cotton balls dipped in melted butter to protect the sharp edge. Small blunt objects (pea sized stones) may pass more easily by administering 2 tablespoons of mineral oil or feeding a couple of tablespoons of Vaseline. HOWEVER, you are assuming the risk of making the problem worse if these techniques fail and the object goes on to perforate the bowel wall or permanently damage it. A dog that might have recovered uneventfully from a simple surgery may end up dying or having a prolonged recovery from peritonitis.Dogs who are suffering from a gastrointestinal obstruction can have a myriad of symptoms. Vomiting is most common, but not always present if the obstruction if far down the intestinal tract. Diarrhea, poor or no appetite, depression, abdominal pain (arched back, or holding a “play bow” position with no intent to play, tensing the muscles when the abdomen is palpated), scant or no stool, and straining to defecate may OR may not be noted. Dogs with protracted vomiting will often become dehydrated very quickly; if they cannot keep down and absorb any liquids they consume, they will become dehydrated in a few hours. Dogs with these signs need prompt veterinary attention.Sometimes a simple physical exam provides all the information a veterinarian needs to diagnose an intestinal obstruction. For example, rocks that are blocking the small intestine can often be detected with abdominal palpation. If the physical exam does not provide enough information to make a diagnosis, your veterinarian will probably choose to run a Complete Blood Count (CBC), Chemistry panel and Electrolyte tests to rule out infections and other causes of these symptoms in addition to taking radiographs (X-rays) of the abdomen. Be aware that not all solid foreign bodies will show up on a radiograph. Rocks are easily seen, but other objects that are hard (i.e. a rubber ball) do not show up. Their presence can still be detected in some cases by the gas pattern that develops in the bowel; normal small intestine has a linear gas pattern, while an obstructed bowel will show a definite “stop” to the gas flow. Linear foreign bodies that are causing the intestine to bunch up may evidence themselves as such on the film; the intestine will be contracted into a smaller mass than normal.Sometimes veterinarians will administer barium as a contrast to “back light” a foreign body; it can also indicate abnormal flow of digesta through the bowel if it fails to travel through the tract at a normal speed. Another invaluable tool for diagnosing foreign bodies in the stomach is the endoscope. This is a tool that is essentially a flexible hose with a bright light and camera on the end. The veterinarian will place the dog under general anesthesia and place the endoscope into the stomach via the mouth. Foreign objects can be seen easily if the stomach is empty of food, and in the duodenum (first part of the small intestine) as well. Some endoscopes are equipped with a basket that will allow the foreign body to be retrieved immediately from the stomach. This has the bonus effect of avoiding surgery, allowing the dog very rapid recovery time. However, if the foreign body is too big, or cannot be pulled out without placing too much tension on the small bowel or esophagus, then surgery will still be necessary.Surgical removal of the blockage can be accomplished be either an incision into the organ that is affected (gastrotomy if it’s the stomach, or enterotomy if it is the intestine) or, in more severe cases where there has been too much trauma to the intestine, via intestinal resection and anastamosis. In this procedure an entire section of the bowel is removed and the ends are carefully reopposed to create an intact tract. Recovery time for resection and anastomosis is longer than for simple gastrotomy or enterotomy because it has greater tendency for leakage or failure to heal, so food is withheld for a longer period of time. I will typically wait 24 hours postoperatively to start feeding after enterotomies and 72 hours for resection and anastomosis. Throughout this period of time the dog is maintained on intravenous fluids, and often injectable antibiotics. The first meals are small, highly digestible and given frequently (every one to two hours). If there is no vomiting the patient is discharged a day later for enterotomies, and 2 to 3 days later for resection and anastomosis. Dogs suffering from peritonitis may be hospitalized for much longer periods of time. Sometimes these dogs will have open drains left in the abdominal wall which require tremendous attention. They may be taken back to surgery for closure of the drainage area if the infection is under control. Total parenteral nutrition (TPN) provides a way to feed these dogs intravenously if the intestine is not working properly and normal food must be withheld for very long periods of time. Short term, and occasionally long term, complications from poor healing are common in dogs with peritonitis.Prevention of this problem has resulted in many mushers moving their dogs to wooden decks to keep the dog away from rocks. Make sure that the platform is far enough away from neighboring dogs to avoid having an enthusiastic digger launch a bunch of yummy stones onto the deck of the your indiscriminate eater. Dawn Brown D.V.M. graduated from the New York State College of Veterinary Medicine at Cornell University and practices small animal medicine and surgery at Carthage, NY. She has been racing sled dogs since 1982.

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