By Dr. Becker
When your dog swallows food, it moves from his mouth, down through his esophagus into a valve in the lower part of the esophagus called the cardiac sphincter and into the stomach. The stomach produces acids and gastric juices that aid the digestive process, and a series of gastric folds also help to grind up and digest the food. The junction between the stomach and first part of the small intestine (the duodenum) is called the pylorus.
Pyloric stenosis describes a non-cancerous thickening of the muscles and mucosa of the pyloric canal that causes it to narrow, inhibiting the flow of partially digested food and liquids from the stomach into the small intestine.
Pets at Risk for Pyloric Stenosis
Pyloric stenosis, which is also known as chronic hypertrophic pyloric gastropathy, can either be congenital (present at birth), or acquired. It’s more common in male than female dogs, and is rarely seen in cats.
The congenital form of the condition is present in certain brachycephalic breeds (dogs with pushed-in faces), including the Boxer, Bulldog and Boston Terrier. Signs appear early, usually between weaning and 1 year of age, because liquids pass much more easily through the pylorus than solid food.
Acquired pyloric stenosis is more common in the Lhasa Apso, Shih Tzu, Pekingese and Poodle, and symptoms usually don’t arise until around age 10. It’s possible that high levels of gastrin, a hormone, may lead to the abnormal thickening process that narrows the pyloric canal. Other risk factors that may play a role in this condition include tumors, chronic gastritis (inflammation of the stomach), gastrointestinal (GI) ulcers and chronic stress.
Symptoms of Pyloric Stenosis
The severity of symptoms is directly related to the extent of the narrowing of the pyloric canal. Since pyloric stenosis disrupts the digestive process, the most common symptoms are chronic, intermittent vomiting and regurgitation of undigested or partially digested food within one to two hours after eating.
In young pets born with the disorder, vomiting often first appears as they are being weaned onto solid foods. Dogs with the condition often lose weight because they aren’t able to absorb nutrients normally. They can also become dehydrated and depressed. They often also have respiratory problems due to aspiration of stomach contents from persistent vomiting. Left untreated, chronic vomiting can lead to significant metabolic problems and secondary pneumonia.
Diagnosing the Disease
If your veterinarian suspects pyloric stenosis, he or she will take a detailed history of your pet’s symptoms and perform a thorough physical examination, including listening to your pet’s lungs with a stethoscope. If the vomiting has been going on for some time, there’s an increased risk for aspiration pneumonia characterized by crackles, wheezes or other harsh lung sounds.
While there’s no specific blood test that indicates pyloric obstruction, if your pet has been vomiting persistently, there will be a number of abnormalities in his bloodwork that your vet can identify. These include low levels of chloride, higher than normal levels of bicarbonate and elevated kidney values resulting from chronic dehydration.
X-rays after barium administration may indicate the barium isn’t flowing normally through the pylorus into the intestines, which is often how the condition is diagnosed. Fluoroscopy is another procedure that can be used to visualize material as it passes through the lower digestive tract. Unfortunately, these imaging tests aren’t always helpful in differentiating between pyloric stenosis and an abscess or tumor in that location.
Another diagnostic test called a gastroscopy may be recommended. It involves feeding an endoscope down through the stomach to visualize and biopsy the pylorus. Since gastric tumors can look quite similar to a pyloric obstruction, it’s very important to obtain biopsies of any abnormal areas during the gastroscopy.
Fluid therapy is very commonly used to correct and prevent dehydration due to chronic vomiting. In serious cases, medical management is necessary to resolve any metabolic abnormalities that have occurred as a result of the pyloric obstruction.
If there is significant obstruction, surgery to widen the pylorus is the treatment of choice. There are several different procedures a soft tissue veterinary surgeon can perform depending on the severity of the disease and the potential for it to get worse. Most dogs respond well to surgery and their prognosis is excellent.
Fortunately, many pets with mild pyloric stenosis and only occasional episodes of vomiting can live normal lives without medical intervention. These pets do best on small, frequent meals of fresh, moisture-rich, species-appropriate foods that are easily digested. I recommend that you finely mince or chop the food and serve it at room temperature. Add probiotics and digestive enzymes to make your pet’s diet optimally digestible and absorbable.