Diseases of the Stomach


Chapter 67 Diseases of the Stomach




VOMITING


Vomiting is a common clinical sign associated with many gastrointestinal (GI) and non-gastrointestinal (non-GI) disorders of dogs and cats. Vomiting is a central nervous system reflex that is integrated in the vomiting center of the brain stem. Afferent stimuli can originate from the cerebral cortex, chemoreceptor trigger zone, pharynx, peritoneum, or abdominal viscera. Vomiting must be differentiated from regurgitation, which is the passive expulsion of undigested food indicating a pharyngeal (swallowing) or esophageal disorder (see Chapter 65).


The metabolic consequences of vomiting vary, depending on the volume and composition of the expulsed fluid. Mild vomiting of short duration usually is not accompanied by overt fluid, electrolyte, or acid-base imbalances. Frequent or profuse vomiting can cause metabolic complications such as dehydration; electrolyte imbalances such as hypokalemia, hyponatremia, and hypochloremia; and acid-base imbalances such as metabolic acidosis or metabolic alkalosis. Metabolic alkalosis is most likely to occur in dogs and cats with vomiting secondary to pyloric obstruction. Other potential complications of vomiting include aspiration pneumonia and reflux esophagitis.





Diagnosis


The diagnostic approach to vomiting is directed toward identifying the underlying disorder (see Table 67-1) and is influenced by whether vomiting is acute or chronic and by the associated historical and physical findings.


Table 67-1 CAUSES OF VOMITING IN DOGS AND CATS









Acute Vomiting (<1wk) Chronic Vomiting (>1–2wk)



































CNS, central nervous system; NSAIDs, nonsteroidal anti-inflammatory drugs.












Treatment


Treatment strategies in the vomiting animal are directed toward the following:








Antiemetics


Antiemetics are used for symptomatic control of acute vomiting on a short-term basis or to control profuse vomiting that results in fluid, electrolyte, or acid-base disturbances.




Metoclopramide


Metoclopramide (Reglan, Robins) (0.2–0.4 mg/kg PO, IM, or SC q8h or 1–2 mg/kg q24h as a constant-rate IV infusion) possesses both central and peripheral antiemetic properties. Central effects are attributed to antidopaminergic activity at the CRTZ and at higher doses, antagonism of 5-hydroxytryptamine type 3 (5-HT3) serotonergic receptors. The peripheral antiemetic effect is due to its stimulant effect on GI motility.


Metoclopramide promotes gastric emptying by increasing the tone and amplitude of gastric contractions and relaxation of the pylorus (Fig. 67-1). Because gastric relaxation and retroperistalsis are key events preceding vomiting, their inhibition may account in part for the drug’s peripheral antiemetic effect.











ACUTE GASTRITIS


Acute gastritis is a common disease in dogs and cats. It is usually a mild, self-limiting condition that rarely warrants biopsy confirmation. Clinical diagnosis of acute gastritis often is made when acute vomiting occurs without apparent cause and resolves on its own in 24 to 48 hours.



Etiology


There are numerous potential etiologies of acute gastritis (see Table 67-1), but the cause often is not determined. Possible causes include the following:













Diagnosis


Because acute gastritis is usually self-limiting, diagnostic evaluations are not usually warranted unless specific historical or physical findings suggest a more serious problem. Response to supportive therapy in 1 to 3 days indirectly supports the diagnosis of uncomplicated acute gastritis as the cause of vomiting.









GASTRIC FOREIGN BODIES


Gastric foreign bodies are most common in dogs owing to their dietary habits and indiscriminant chewing behavior.






Treatment


When a gastric foreign body is identified radiographically, consider whether immediate removal is necessary.






Endoscopic Removal


Attempt endoscopic removal of gastric foreign bodies before gastrotomy, because most foreign bodies can be removed in this manner.







GASTRODUODENAL ULCERATION


For the purposes of this discussion, gastroduodenal ulceration is defined as mucosal defects associated with bleeding, which includes petechiae, erosions, and ulcers. Clinical recognition of gastroduodenal ulceration as a complicating factor in many disorders is becoming more common, most likely due to the increased use of endoscopy.



Etiology


Many disorders have been associated with gastroduodenal ulceration (Table 67-2). Ulceration is more likely when two or more risk factors are present. General mechanisms of gastroduodenal ulceration include direct damage to the gastric mucosal barrier, increased gastric acid secretion, delayed gastric epithelial renewal, and decreased gastric mucosal blood flow.






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Aug 27, 2016 | Posted by in SMALL ANIMAL | Comments Off on Diseases of the Stomach

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