It is important that you make sure that your pet 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 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.
