Page 493 - Small Animal Internal Medicine, 6th Edition

CHAPTER 30 Disorders of the Stomach 465

gastroduodenoscopy (see Fig. 27.21). There may be only one vomiting is sometimes described as “projectile.” Animals are
worm causing clinical signs, and it can be difficult to find if otherwise clinically normal, although they may lose weight
VetBooks.ir it is a juvenile worm or if it is attached within the pylorus. due to inadequate caloric retention. Some cats with pyloric
stenosis vomit so much that secondary esophagitis, mega-
Alternatively, an empirical treatment trial (as described here)
esophagus, and regurgitation occur, confusing the clinical
is reasonable.
picture. Hypochloremic-hypokalemic metabolic alkalosis
Treatment sometimes occurs, but it is inconsistent and nonspecific for
Pyrantel pamoate or ivermectin is usually effective. If the gastric outflow obstruction (excessive loss of gastric secre-
parasite is found during endoscopy, it can be removed with tions for any reason and aggressive diuretic therapy are
forceps. common causes).
Prognosis Diagnosis
Vomiting usually stops as soon as the worm(s) are removed Gastric outflow obstruction is diagnosed based on plain/
or eliminated. contrast radiographs, ultrasonography, gastroduodenos-
copy (i.e., there are typically prominent folds of normal-
OLLULANUS TRICUSPIS appearing mucosa at the pylorus), and/or exploratory
surgery (i.e., the surgeon can open the stomach and try
Etiology to pass a finger through the pylorus to assess its patency)
Ollulanus tricuspis is a nematode with a direct life cycle as well as eliminating extraalimentary tract diseases (see
transmitted via vomited material. Box 26.6). Once diagnosed, the outflow area should be
inspected endoscopically or surgically, and infiltrative pyloric
Clinical Features disease ruled out through biopsy. At surgery the serosa
Cats are the most commonly affected species, although dogs appears normal, but the pylorus is usually thickened when
and foxes are occasionally infected. Vomiting is the princi- palpated.
pal clinical sign, but clinically normal cats may harbor the
parasite. Gastric mucosal lesions may or may not be seen in Treatment
infested cats. Surgical correction is required. Pyloroplasty (e.g., a Y-U–
plasty) is more consistently effective than pyloromyotomy.
Diagnosis Improperly performed pyloroplasty or pyloromyotomy can
Cattery situations promote infection because the parasite is cause perforation or worse obstruction. Some clinicians rou-
passed directly from one cat to another. However, occasion- tinely performed one of these pyloric outflow procedures
ally cats with no known contact with other cats are infected. whenever an exploratory laparotomy fails to reveal the cause
Looking for parasites in gastric washings or vomited mate- of vomiting; this is a very poor practice and should not be
rial with a dissecting microscope is the best means of diag- done.
nosis. The parasite can be seen occasionally in gastric
mucosal biopsy specimens. Prognosis
Surgery should be curative, and the prognosis is good.
Treatment and Prognosis
Therapy is uncertain, but fenbendazole might be effective. GASTRIC ANTRAL MUCOSAL
Occasionally animals have severe gastritis and become HYPERTROPHY
debilitated.
Etiology
GASTRIC OUTFLOW OBSTRUCTION/ Antral mucosal hypertrophy is idiopathic. Gastric outflow
GASTRIC STASIS obstruction is caused by proliferation of nonneoplastic
mucosa that occludes the distal gastric antrum (Fig. 30.2).
BENIGN MUSCULAR PYLORIC This disorder is different from benign muscular pyloric ste-
HYPERTROPHY (PYLORIC STENOSIS) nosis (i.e., where normal mucosa is thrown up into folds
secondary to submucosal thickening).
Etiology
The cause of benign muscular pyloric hypertrophy is uncer- Clinical Features
tain. Some research suggests that gastrin promotes develop- Principally found in older, small-breed dogs, antral hyper-
ment of pyloric stenosis. trophy clinically resembles pyloric stenosis (i.e., animals
usually vomit food, especially after meals).
Clinical Features
Benign muscular pyloric stenosis typically causes persis- Diagnosis
tent vomiting in young animals (especially brachycephalic Gastric outlet obstruction is diagnosed radiographically,
dogs and Siamese cats) but can be found in any animal. ultrasonographically, or endoscopically; however, definitive
Affected animals usually vomit food shortly after eating. The diagnosis of antral mucosal hypertrophy requires mucosal