Answers and Discussion
Case #16 -- Pyloric Obstruction
Answers and Discussions to the Questions:
- What differential diagnoses should you consider in this case?
Differentials should include pancreatitis, pyloric/small intestinal obstruction (foreign
body, neoplasia), toxins (ibuprofen, rodenticide) or infectious disease (parvo, HGE).
However, with this history you can rule many of these out. With pancreatitis
you usually don't see hematemesis and it should not be going on for a month. The
same goes for toxins and infectious disease--they should not be going on for a month or
the animal should be much more ill by now.
- Why is the respiratory rate so low in "Honey"?
The extreme metabolic alkalosis
(Potassium = 2.8 meq/L. Chloride = 65 meq/L. Bicarbonate = 36.4 meq/L)
results in a slow
shallow respiratory pattern to attempt to conserve CO2 and
thus compensate for the
alkalosis.
- What radiographic findings do you see?
The duodenum is dilated. There is loss of serosal detail in the abdomen suggesting
peritoneal effusion. Most importantly, there is a gas opacity ventral to the liver
on the right lateral view of the thorax. Gas opacities are also identified cranial
to the stomach in the area of the left side of the liver. This suggests there is
free gas in the abdomen due to the rupture of a viscus. IMPORTANT: Before
doing an abdominal tap, always take your abdominal radiographs first. Introducing
the needle to the belly in turn introduces air into the abdomen. You don't want to
be confused as to whether there is a ruptured viscus or not.
- What initial medical treatments would you institute?
A 1/4-shock dose of fluids should be given IV. Continue fluid therapy--0.9%
NaCl with KCl added (30 or 40meq) is best since electrolytes are low. (Keep a close
eye on potassium levels.) Add glucose if signs of sepsis are present.
Antibiotics should be given IV--ampicillin and enrofloxacin are best. GI protectants
should be given, like sucralfate and either ranitidine or pepcid.
- When should you take this patient to surgery?
Never let the sun set on a small bowel obstruction. This axiom is
even more true the closer the obstruction is to the pylorus.
"Stabilization" of the patient before surgery includes shock fluids and the
initial dose of antibiotics.
- Follow-Up: At surgery, there was 2.5 liters of fluid in the
abdomen. The stomach was thickened. There was evidence that other small
ruptures of the stomach had occurred before, indicating this was a chronic problem.
Now, approximately 85% of the stomach was involved in a mass at the pylorus. A
frozen section of the mass was submitted for immediate histopathology. It was a
gastric carcinoma. The owners elected euthanasia intraoperatively.
Pyloric Obstruction Pearls
- Metabolic alkalosis presents with slow and shallow respiration.
- Electrolytes in metabolic alkalosis always show a decrease in potassium, chloride, and
sodium. Also the bicarbonate concentration is elevated.
- Treat initially with shock doses of fluids, antibiotics and GI protectants.
- Always radiograph an abdomen before you tap it!
- Free gas in the abdomen IS a surgical emergency!
- A small bowel obstruction IS a surgical emergency!
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Copyright 2000, Wayne E. Wingfield,
and Brenda McClelland, DVM Colorado State University
This page was last edited: 03/01/00