Diagnostic Evaluation<\/h2>\n
Acute gastroenteritis is among many potential causes of acute vomiting and diarrhea (Table 1<\/strong>). However, in many cases, the cause of primary acute gastroenteritis is not determined. Rapid resolution of clinical signs often means that extensive diagnostic evaluation is unnecessary.<\/p>\n No specific physical examination findings are pathognomonic for acute gastroenteritis, and some dogs do not have any significant abnormalities. Findings consistent with acute gastroenteritis include lethargy, pytalism, and abdominal discomfort.<\/p>\n It is particularly important to assess the patient\u2019s hydration status and palpate the abdomen carefully, checking for physical examination findings that would warrant further diagnostic evaluation (ie, abnormalities that suggest the problem is more significant than straightforward acute gastroenteritis) (Table 2<\/strong>). Findings that indicate dehydration include dry oral mucous membranes, prolonged capillary refill time, and prolonged skin tent. Tachycardia, weak pulses, and cool extremities are consistent with hypovolemia.<\/p>\n Patients with a normal physical examination and mild clinical signs may not require laboratory testing on initial presentation. However, laboratory testing may be indicated to rule out extra-gastrointestinal causes of acute gastrointestinal signs, such as acute kidney injury, acute hepatitis, and pancreatitis, and metabolic complications of acute gastroenteritis, such as electrolyte and acid base abnormalities.<\/p>\n When performed, laboratory testing should include a complete blood count, serum biochemical profile, and urinalysis. Measurement of serum canine pancreas-specific lipase concentration may also be indicated to diagnose pancreatitis, and baseline serum cortisol concentration may be measured in order to exclude hypoadrenocorticism.<\/p>\n Additional laboratory testing for infectious disease should be considered based on geographic location and signalment. For example, serology assists in diagnosis of Salmon poisoning disease in the Pacific Northwest. In dogs with diarrhea, fecal flotation and direct smear examination should be performed to screen for primary or concurrent parasitism (Figure 1<\/strong>).<\/p>\n FIGURE 1. Gastric nematode presumed to be Physaloptera rara <\/em>visualized during gastroscopy. The hemorrhage observed is associated with gastric biopsy.<\/p><\/div>\n In patients with clinical findings (Table 2<\/strong>) or laboratory results that suggest a serious underlying cause, or those that do not respond to therapy, further diagnostic evaluation is indicated. Early identification is especially important in patients requiring surgical intervention, such as those with an obstructive intestinal foreign body (Figure 2<\/strong>).<\/p>\n FIGURE 2. Fabric gastric foreign body visualized during gastroscopy.<\/p><\/div>\n Abdominal ultrasonography and\/or abdominal radiography are strongly advised in patients presenting with abdominal pain to screen for diseases requiring surgical intervention. It is important to remember that pancreas-specific lipase concentrations can be increased in dogs and cats with gastrointestinal foreign bodies. Therefore, it is essential to rule out gastrointestinal foreign bodies with abdominal radiographs and, possibly, abdominal ultrasound before pancreatitis is diagnosed. If there is high suspicion for a gastrointestinal foreign body that may have been obscured by fluid or gas, diagnostic imaging should be repeated.<\/p>\n Read the article, Endoscopic Foreign Body Retrieval<\/strong><\/a>.<\/p><\/blockquote>\n When acute gastroenteritis is the primary cause of vomiting and\/or diarrhea, the symptomatic treatments discussed in this article are appropriate for therapy. However, if gastroenteritis occurs secondary to an underlying disease, such as hypoadrenocorticism, it is essential to treat the primary condition in addition to providing symptomatic and supportive therapy.<\/p>\n This article emphasizes symptomatic treatment of primary acute gastroenteritis rather than detailing specific treatment of serious underlying diseases that may cause similar clinical signs.<\/p>\n For acute gastroenteritis, antiemetic therapy is often used for the initial 24 to 48 hours when vomiting is a prominent clinical sign (Table 3<\/strong>). Benefits include:<\/p>\n Take care not<\/em> to mask ongoing disease with prolonged (i.e., greater than 3 days) antiemetic therapy. In addition, to reduce the risk of gastrointestinal perforation and avoid delay of surgical intervention by masking clinical signs of intestinal obstruction, do not<\/em> administer antiemetic or prokinetic drug therapy when a foreign body is suspected or confirmed.<\/p>\n Several classes of antiemetic drugs are used in small animal medicine. Occasionally, refractory cases require the use of more than one of these drugs at the same time.<\/p>\n Ondansetron and dolasetron are serotonin (5-HT3<\/sub>) antagonists with potent antiemetic activity that are commonly used off-label to control nausea in dogs and cats. This class of drug blocks the chemoreceptor trigger zone and vagal afferent pathways involved in emesis. In our experience, these drugs are very effective for control of vomiting in dogs and cats.<\/p>\n Substance P is a neurotransmitter that binds to neurokinin-1 (NK-1) receptors and can result in vomiting. Therefore, NK-1 receptor antagonists are powerful antiemetics effective at treating both peripheral and central causes of vomiting.<\/p>\n Maropitant, a NK-1 receptor antagonist, is currently the only licensed antiemetic for use in dogs and cats and, in our opinion, is very effective. This drug may also have an analgesic effect and, thus, is widely used in patients with vomiting and abdominal pain, such as those with pancreatitis.1<\/sup> The efficacy of maropitant for the control of presumed nausea is controversial as some studies have shown a benefit while others have not documented a benefit.2-6<\/sup><\/p>\n While maropitant is not licensed for IV use, we and other clinicians have administered it by this route\u2014at a dose of 1 mg\/kg Q 24 H\u2014without apparent adverse effects. The manufacturer recommends that after 5 days of continuous administration the drug should be discontinued for 24 hours to avoid drug accumulation; then treatment can be restarted, if necessary.<\/p>\n Antidopaminergic agents, such as metoclopramide, have both central and peripheral antiemetic effects and are used off-label in dogs and cats. Metoclopramide also stimulates the release of acetylcholine from postganglionic nerves in the peripheral nervous system, which leads to increased gastric contractions and increased gastroesophageal sphincter tone. This promotility effect may also contribute to its antiemetic properties.<\/p>\n Metoclopramide can cause neurologic side effects, including excitement and restlessness. The short half-life of this drug necessitates frequent dosing. In our experience, it is most effective when delivered via an IV constant rate infusion but is not as effective as maropitant, ondansetron, or dolasetron. Metoclopramide may not have a direct central antiemetic effect and is a less effective antiemetic agent in cats than in dogs.7<\/sup> For this reason, we seldom use it for this purpose in the former unless a prokinetic agent is also indicated.<\/p>\n Phenothiazines, such as chlorpromazine and prochlorperazine, are potent centrally acting antidopaminergics that inhibit the vomiting center and chemoreceptor trigger zone. This class of drug also has antihistaminergic and anticholinergic properties.8<\/sup><\/p>\n They are not<\/em> recommended in hypovolemic patients due to potential for hypotension, and these drugs are not licensed for use in dogs and cats. Phenothiazines can cause mild sedation and are no longer commonly used due to the availability of other effective antiemetic drugs.<\/p>\n Sucralfate is a sulfated disaccharide that binds to the acidic moieties of exposed collagen in damaged mucosa, creating a protective barrier against further acid damage. It also stimulates prostaglandin release and cellular proliferation at sites of ulceration and increases mucus production and bicarbonate secretion.<\/p>\n Sucralfate is recommended only in cases of suspected gastrointestinal erosion or ulceration, such as those that present with hematemesis or melena. It can interfere with absorption of other drugs, and is typically given at least 2 hours before or after other medications.<\/p>\n Famotidine and ranitidine are histamine-2 (H2<\/sub>)-receptor antagonists that competitively inhibit histamine-induced acid secretion by the gastric parietal cells.<\/p>\n Famotidine is more effective at increasing canine gastric pH compared with ranitidine, but ranitidine also has anticholinesterase activity. This activity may result in some prokinetic action but in studies was only as effective as a saline placebo at increasing gastric pH in dogs and cats; thus, it is not recommended for its acid-suppressing effects.9,10<\/sup><\/p>\n H2<\/sub>-receptor antagonists are less efficacious than proton pump inhibitors (PPIs) in vivo<\/em>, but the degree of gastric acid inhibition necessary for therapeutic effect is unknown. H2<\/sub>-receptor antagonists may also have cytoprotective properties.11,12<\/sup><\/p>\n Omeprazole and pantoprazole are PPIs that irreversibly inhibit acid production by gastric parietal cells. This class of drug is more efficacious and has a longer duration of activity than H2<\/sub>-receptor antagonists; it may also exert a cytoprotective effect by enhancing prostaglandin synthesis.9-11,13<\/sup><\/p>\n In dogs and cats, twice-daily dosing of omeprazole is more effective at reducing gastric acid secretion than once-daily administration.9,10<\/sup> Coadministration of famotidine and pantoprazole does not seem to be any more effective than therapy with pantoprazole alone and, thus, there is no benefit in using a H2<\/sub>-receptor antagonist for the first 24 hours of therapy.14<\/sup><\/p>\n Because of this, PPIs are the preferred treatment for dogs and cats known or suspected to have esophageal or gastroduodenal ulceration.11,14<\/sup><\/p>\n Anecdotally, some dogs and cats with acute gastroenteritis, but no other findings that indicate gastroduodenal ulceration, such as hematemesis or melena, appear to respond favorably to acid-suppressing drugs. However, use of these drugs has not proven beneficial in any studies in dogs and cats with uncomplicated gastroenteritis; thus, they are not routinely recommended for brief episodes.<\/p>\n In humans, long-term use of PPIs has been associated with such side effects as cobalamin deficiency, iron deficiency, hypomagnesemia, increased susceptibility to pneumonia, enteric infections, fractures, hypergastrinemia, and cancer.15<\/sup> To our knowledge, other than hypergastrinemia, the side effects described above have not been reported in dogs and cats receiving long-term treatment with PPIs.<\/p>\n Misoprostol is a synthetic prostaglandin E1 that acts on parietal cells to inhibit secretion of gastric acid. Additionally, it has a cytoprotective effect by increasing secretion of mucus by gastric goblet cells, increasing gastric mucosal blood flow and increasing turnover of gastric mucosal cells.<\/p>\n PPIs and H2<\/sub>-receptor antagonists are thought to be more effective for treatment of gastrointestinal ulcers, and misoprostol may cause vomiting, diarrhea, and abdominal pain. Use of misoprostol is, therefore, not advised in dogs with acute gastroenteritis unless gastroduodenal ulceration associated with nonsteroidal anti-inflammatory drug (NSAID) use is thought to be the cause.<\/p>\n Most cases of uncomplicated acute gastroenteritis that present with either small or large bowel diarrhea resolve without therapeutic intervention. Cases that present with diarrhea should have a fecal examination and consider empirical deworming with a broad spectrum anthelminthic. However, there are a few options for symptomatic treatment of diarrhea.<\/p>\n Loperamide, an opioid antimotility drug, has been used off-label in dogs with diarrhea. It decreases intestinal motility and reduces mucosal secretions. Doses used to treat diarrhea can cause neurologic toxicity in dogs with the ABCB1<\/em> (formerly MDR1<\/em>) mutation; therefore, avoid this drug in all dogs carrying this allele and at-risk dog breeds (ie, Australian shepherd, Shetland sheepdog, long-haired whippet, collie, English shepherd, German shepherd) that have an unknown status. We do not<\/em> recommend use of this drug for treating dogs or cats with acute gastroenteritis due to this potential toxicity and because the diarrhea associated with gastroenteritis is usually self-limiting.<\/p>\n![\"T1511F04_Table01\"](\"https:\/\/todaysveterinarypractice.com\/wp-content\/uploads\/sites\/4\/2015\/11\/T1511F04_Table01.jpg\")
<\/a><\/p>\nPhysical Examination<\/strong><\/h3>\n
<\/a><\/p>\nLaboratory Analysis<\/strong><\/h3>\n
<\/a><\/a>Imaging<\/strong><\/h3>\n
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Learn More<\/strong><\/h2>\n
Therapeutic Approach<\/h2>\n
Antiemetic Drugs<\/h2>\n
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<\/a><\/p>\nOndansetron and Dolasetron<\/strong><\/h3>\n
Maropitant<\/strong><\/h3>\n
Metoclopramide<\/strong><\/h3>\n
Phenothiazines<\/strong><\/h3>\n
Gastroprotectants<\/strong><\/h2>\n
Sucralfate<\/strong><\/h3>\n
Famotidine and Ranitidine<\/strong><\/h3>\n
Omeprazole and Pantoprazole<\/strong><\/h3>\n
Misoprostol<\/strong><\/h3>\n
Antidiarrheal Therapy<\/h2>\n
Loperamide<\/strong><\/h3>\n
Probiotics<\/strong><\/h3>\n