Besides hiatal hernia, the most common abnormality involving the stomach with a suspected heritable etiology is pyloric stenosis, which affects brachycephalic dog breeds (Boxers, Boston Terriers, English Bulldogs) and Siamese cats. Pyloric stenosis or pyloric muscular hypertrophy results from muscular thickening of the pyloric sphincter, which obstructs pyloric outflow. Clinical signs reflect delayed gastric emptying and usually manifest as vomiting of food several hours after a meal but may also include poor weight gain, aspiration pneumonia, depression, and dehydration. Diagnosis is aided by contrast imaging and endoscopy, which is often combined with biopsy to exclude neoplasia. Surgical treatment is recommended to relieve the obstruction. Medical treatment of esophagitis, acid-base abnormalities, and dehydration should be instituted before surgery.
Pyloric stenosis, pyloromyotomy site. Illustration by Dr. Gheorghe Constantinescu.
Abomasal emptying defect of sheep is a dysautonomia characterized by functional obstruction of the pyloric sphincter, possibly due to neurotoxicity of the celicomesenteric ganglia. It is well described in Suffolk sheep with few cases reported in Hampshire, Dorset, and Texel breeds. The etiology is unknown; it may be hereditary or that certain genotypes predispose to the condition. Pedigree analysis of affected flocks does not show a simple inheritance pattern. Clinical signs include weight loss, anorexia, depression, dyspnea, decreased rumen motility, and progressive distention of the right ventral abdomen. Even with abomasotomy, the prognosis is poor to grave.