Overview of Canine Pyloric Obstruction or Stenosis
The pylorus is the lower portion of the stomach that leads into the small intestine of the dog. Pyloric obstruction or stenosis usually refers to a thickening of the various layers of muscle and mucosa (stomach lining tissue) that make up this region, leading to obstruction of flow of food or water through the stomach. This thickening is a benign, non-cancerous process.
Pyloric obstruction or stenosis is most commonly seen in brachycephalic (short-faced) breeds of dog such as boxers, Boston terriers and bulldogs. These dogs tend to be young and predominantly male. It can also occur as a more chronic condition in small breeds of dog such as Lhasa apso, shih tzu and Maltese terrier. These dogs tend to be middle-aged to older.
If food and water cannot move through the stomach, the dog will regurgitate or vomit and become sick, dehydrated, and depressed. Untreated, the chronic vomiting can lead to significant metabolic problems, weight loss and the risk of aspiration pneumonia. This combination of problems could easily become fatal.
What to Watch For
Young brachycephalic breed of dog
Older small breed dog
In young animals, vomiting often occurs at the time of weaning onto solid foods.
Diagnosis of Pyloric Obstruction/Stenosis in Dogs
A detailed history and physical examination can initially lead your veterinarian to suspect pyloric obstruction. Additional tests are necessary to make a definitive diagnosis. Tests may include:
Radiographs (X-rays) may be taken of the abdomen, but neither plain radiographs, contrast radiographs using liquid barium or ultrasound are as good as gastroscopy for diagnosing the type of pyloric disease present.
Gastroscopy involves placing an endoscope down through the stomach in order to visualize and biopsy the pylorus.
Many changes may be present in the blood work of an animal that has been vomiting for some time. The loss of acid from the stomach will cause a loss of chloride and a relative increase in the amount of alkali present (metabolic alkalosis). Elevations in kidney parameters can occur, reflecting dehydration.
There is no specific blood test to determine pyloric obstruction or stenosis.
Treatment for Pyloric Obstruction/Stenosis in Dogs
Medical management is important to correct the metabolic abnormalities of chronic pyloric obstruction, but definitive treatment requires surgery.
Your pet may be given intravenous fluids, antacids and antibiotics prior to anesthesia, in order to be in as stable a condition as possible going into the surgical procedure.
There are multiple different types of corrective surgery for the thickened pylorus and the type selected can depend on the surgeon’s experience and which layers of the pylorus are affected by the disorder.
Whichever type of surgery is performed, the aim of the procedure is to restore the normal size of the opening from the pylorus to the duodenum, the first part of the small intestine.
Home Care and Prevention
Your dog’s abdominal skin incision will need to be monitored for swelling, redness or discharge. Staples or stitches can be removed in 10 to 14 days.
Your pet will have received pain-killers (analgesics) during the period of hospitalization and these may continue in oral form when he goes home.
Follow your veterinarian’s recommendations regarding feeding and contact your veterinarian if your dog begins vomiting or does not eat.
The cause of this disease is not known. For this reason there is nothing an owner can do to prevent the problem from occurring. Prompt veterinary care for your vomiting pet is the best course of action.
In-depth Information on Canine Pyloric Obstruction or Stenosis
Many disorders can lead to vomiting and most of them are far more common than pyloric obstruction or stenosis. These conditions may include:
Gastrointestinal foreign bodies are ingested material that is either not digested or slowly digested. These can cause obstruction or irritation to the stomach and intestinal tract. Common foreign bodies include rocks, bones, plastic toys, socks, pantyhose and various other objects. String, yarn and thread can create linear foreign bodies. These can get anchored at the base of the tongue or the stomach and cause the bowel to bunch up or be plicate. Young dogs are more commonly interested in foreign bodies and on physical examination they may not be painful on abdominal palpation. Radiography and endoscopy will help discriminate a foreign body from pyloric obstruction or stenosis.
Vomiting can be a component of many viral causes of gastroenteritis, such as distemper or parvovirus. Again, young unvaccinated dogs may be affected and are often painful on abdominal palpation. These animals usually have concurrent diarrhea and other clinical abnormalities that are quite different from pyloric obstruction or stenosis.
Several metabolic disorders can lead to vomiting such as uremia secondary to kidney disease, diabetes, and liver insufficiency. Laboratory analysis of blood samples obtained from the patient should lead your veterinarian to pursue these disorders.
Diseases of the pancreas such as pancreatitis, pancreatic tumors and pancreatic abscesses can produce vomiting. Most animals with pancreatic disorders are painful on abdominal palpation.
Peritonitis is an inflammation of the peritoneum, the lining of the abdomen. The most common cause of peritonitis results from intestinal or gall bladder rupture, and animals have vague clinical signs often accompanied by vomiting and diarrhea. Again, dogs with peritonitis are usually painful on palpation of their abdomen, but this may be localized rather than generalized, dependent on the extent of the problem.
Gastric tumors can cause vomiting. The most common type of tumor in dogs is called a gastric adenocarcinoma, and it occurs most commonly in the pyloric region and therefore needs to be differentiated from benign pyloric obstruction typically seen in middle aged to older small breed dogs. Endoscopy with biopsies will be important to discriminate these two diseases.
Gastric ulceration is most often secondary to taking anti-inflammatory medication such as aspirin, ibuprofen, phenylbutazone etc. The pylorus is a common location for an ulcer to occur. Endoscopy is the most sensitive test to allow visualization and biopsy of an ulcer.
It is important that you make sure that your dog is truly vomiting and not simply regurgitating food. Vomiting is an active process involving contraction of the abdominal musculature and partially digested food as opposed to passive regurgitation in which undigested food simply falls from the mouth when the head is lowered toward the ground.
Vomiting is the most common clinical sign of pyloric obstruction, but it may be intermittent and may not occur for several hours after feeding. Vomiting may occur several times a day or only once or twice a week. Since pyloric stenosis occurs frequently as a congenital problem your puppy is born with, vomiting often begins when after beginning to eat solid food.
Diagnostic Test In-Depth for Pyloric Obstruction/Stenosis in Dogs
Several findings may be noted by your veterinarian during a physical examination such as thinness, lethargy and dehydration, which can be detected by tenting of the skin when it is picked up and dryness in the mouth. Most animals with pyloric stenosis or obstruction are not painful during abdominal palpation.
Your veterinarian will carefully listen to your dog’s chest with a stethoscope. If vomiting has been going on for some time, there is an increased risk for aspiration pneumonia that may lead to crackles, wheezes or other harsh lung sounds.
Plain radiographs (X-rays) of the abdomen may be helpful to rule out other causes of vomiting, but they are unlikely to be diagnostic for pyloric obstruction or stenosis.
Your dog can swallow liquid barium before radiographs taken of the abdomen. This may show a delay in emptying of the stomach or a thickening of the stomach wall, and it can show an abnormal pattern or filling defect in the pylorus. This would not discriminate between benign pyloric obstruction or stenosis and, say, a tumor or abscess.
Ultrasound may determine that the cause of the vomiting lies in an abnormal structure in the pylorus, but would be unable to differentiate the cause. Ultrasound can be helpful to inspect regional lymph nodes that could be enlarged in the case of infection or tumor.
The single best diagnostic tool is endoscopy. This is placement of a flexible camera down the esophagus and into the stomach to allow visualization of the inside and even the ability to pass through the pylorus and into the duodenum.
Because gastric tumors and benign pyloric obstruction or stenosis can look extremely similar, it is essential to obtain biopsies of any abnormal areas during the time of endoscopy. These are obtained by passing an instrument down the endoscope and pinching off tiny pieces of the abnormal tissue that can be submitted to a pathologist for examination and identification.
There are no specific laboratory abnormalities for pyloric stenosis or obstruction. However, bloodwork is important to determine the extent of metabolic abnormalities present as a result of chronic vomiting, so that they may be corrected and to screen for other infectious or metabolic causes of vomiting.
Treatment In-Depth for Pyloric Obstruction/Stenosis in Dogs
The effects of chronic vomiting or regurgitation must be addressed in treatment. This will include placement of an intravenous catheter to initiate fluid therapy, not only to correct dehydration but also to correct for electrolyte imbalance.
Anti-emetic drugs. Chronic vomiting can lead to the acidic content of the stomach irritating and inflaming the esophagus. Your dog may also receive antacids such as Tagamet® (cimetidine).
Antibiotics. Concerns about gastric or esophageal ulceration and the possibility of having aspiration pneumonia, may prompt your vet to place your dog on antibiotics. If chest radiographs confirm the presence of pneumonia, then the selection of antibiotic may be based on a tracheal wash.
Surgery. All of the above treatments will be beneficial and supportive, but they do not address the pyloric disorder itself. To correct the problem surgery is indicated. Medical treatment also helps to insure that your animal is in the best possible shape for anesthesia and corrective stomach surgery.
The pyloric obstruction or stenosis can involve the muscular portion of the stomach, the lining layer or mucosa of the stomach, or both. Different surgical procedures were originally developed to address these different conditions.
The simplest procedure involves cutting the thickened muscular layer of the pylorus and leaving the mucosa intact. This does not allow inspection or biopsy of the mucosa and is probably only a temporary solution. For these reasons it is no longer recommended.
Surgical resection. In some cases, the thickening may be such that altering the size of the outflow from the pylorus is not enough. In this instance a corrective surgery that either entirely removes the region of obstruction or stenosis, or by-passes that area of the stomach, may be more appropriate. In both examples the stomach would be joined to the small intestine so that food and liquids could resume their normal passage through the digestive system. Again, these procedures can be performed using suture material or surgical stapling equipment.
Other techniques cut through all the layers and then widen the lumen of the pylorus. These procedures can be performed using suture material or surgical stapling equipment.
During any gastrointestinal surgery, care is taken not to contaminate the abdomen with any stomach or intestinal contents and the abdomen would be thoroughly irrigated during and after completion of the procedure.
Removed tissue is submitted to a pathologists for histopathological evaluation to ensure that the disease is benign.
Analgesics. Your dog will have received analgesics (pain-killers) in injectable form before and after the procedure. Oral analgesics may be prescribed for a short time, when your dog goes home.
Intravenous fluids. Fluids will continue after surgery to maintain normal hydration. The day after surgery small amounts of water will be offered. If no vomiting occurs, small amounts of moist food will be offered about 24 hours after the surgery. If this is kept down, intravenous fluid support will be removed and your dog will usually be able to go home.
Motility drugs. Because the surgical procedures involve the outflow portion of the stomach, sometimes the coordination and rhythm of the stomach’s contractions need some medical assistance. If your dog does vomit after surgery, medications e.g. Reglan® (metaclopromide), may be given to enhance and assist in the flow of food and liquid through the stomach. This may be continued for a short time at home.
Blood tests. Blood samples may be obtained in the early postoperative period, before eating and drinking has resumed, to make sure that electrolytes remain in balance.
Your pet will have been shaved along his belly and have an abdominal incision. Check the site for swelling, redness or discharge on a daily basis. If you have concerns do not hesitate to contact your veterinarian. If licking of the incision occurs, an Elizabethan collar may become necessary. The staples or stitches will need to be removed in 10 to 14 days.
It will be important to monitor eating and drinking. Offer small amounts of water at a time rather than filling a bowl full, which may cause your dog to gorge and vomit. Do the same with solid food, offering the same total amount of food each day as normal, but, when possible, divide it into several feedings. After a week or so, you can resume your regular feeding regime.
Continue with antacids, antibiotics, and any other treatments sent home with your pet.
Allow your dog to stay quiet and rested for the first few weeks after surgery, just taking slow leash walks, and eliminating anything excessive. Be particularly observant of eating and drinking habits, especially if your have more than one pet.
Do not offer your pet any chew toys, pig’s ears, rawhide, bones or anything of that nature for several weeks after the procedure. If vomiting recurs, even sporadic, then you should not hesitate to consult with your veterinarian.
Prevention In-depth for Pyloric Obstruction/Stenosis in Dogs
The exact cause of pyloric obstruction or stenosis is unknown. It is more commonly seen in the short-faced brachycephalic breeds of dogs but clearly only a small number have this problem. Because there is no known genetic component to the disorder, knowing whether the sire and dam of a brachephalic puppy has had this disease would be of no benefit.
Providing a safe environment for your dog with regard to potential gastric foreign bodies and ensuring your pet is properly vaccinated will decrease the likelihood of some of the causes of vomiting that may be mistaken for pyloric obstruction or stenosis.
All animals may occasionally vomit, but should this persist or be intermittently recurrent, particularly in a young animal, then you should seek immediate veterinary attention. It does not take long for a puppy to become extremely dehydrated and sick with frequent bouts of vomiting.
Early diagnosis of pyloric obstruction or stenosis and appropriate surgical correction has a good prognosis that should not have any long-standing effects on your dog’s digestive system.