Peer Reviewed SYMPTOMATIC MANAGEMENT OF PRIMARY ACUTE GASTROENTERITIS Symptomatic Management of Primary Acute Gastroenteritis Yuri Lawrence, DVM, MA, MS, Diplomate ACVIM (Small Animal Internal Medicine), and Jonathan Lidbury, BVMS, MRCVS, Diplomate ACVIM (Small Animal Internal Medicine) & ECVIM (Companion Animal) Texas A&M University Acute gastroenteritis is a term used to describe a TABLE 1. syndrome characterized by the sudden onset of Selected Causes of Secondary Acute vomiting and/or diarrhea caused by gastrointestinal Gastroenteritis mucosal inflammation. • Prototheca species Algal This diagnosis is seldom confirmed by Bacterial • Campylobacter species histopathologic evaluation; instead, it is based on • Clostridia species a consistent clinical presentation and exclusion of • Escherichia coli • Neorickettsia helminthoeca other potential causes for the patient’s clinical signs. • Salmonella species Mucosal inflammation is assumed, but not proven Drugs • Antibiotics to be present. Therefore, acute gastroenteropathy is • Cyclosporine perhaps a more appropriate name. • Glucocorticoids • Mycophenolate • Nonsteroidal anti-inflammatory drugs DIAGNOSTIC EVALUATION Acute gastroenteritis is among many potential Parasitic • Ancylostoma caninum • Ollulanus tricuspis causes of acute vomiting and diarrhea (Table 1). • Physaloptera species However, in many cases, the cause of primary acute • Strongyloides species gastroenteritis is not determined. Rapid resolution • Toxoascaris leonina of clinical signs often means that extensive diagnostic • Toxocara canis evaluation is unnecessary. Protozoal • Cryptosporidium parvum • Giardia species • Isospora canis Physical Examination No specific physical examination findings are Systemic • Bacterial cholecystitis disease • Gallbladder mucocele pathognomonic for acute gastroenteritis, and some • Gastric dilatation and volvulus dogs do not have any significant abnormalities. • Hepatic disease Findings consistent with acute gastroenteritis include • Hypoadrenocorticism • Pancreatitis lethargy, pytalism, and abdominal discomfort. • Pyometra It is particularly important to assess the patient’s • Renal disease hydration status and palpate the abdomen carefully, • Sepsis checking for physical examination findings that • Septic peritonitis • Splenic torsion would warrant further diagnostic evaluation (ie, abnormalities that suggest the problem is more Toxins • Chocolate • Lead significant than straightforward acute gastroenteritis) • Mushrooms (Table 2). Findings that indicate dehydration • Organophosphates include dry oral mucous membranes, prolonged • Xylitol • Zinc capillary refill time, and prolonged skin tent. Tachycardia, weak pulses, and cool extremities are Viral • Canine coronavirus • Canine parvovirus consistent with hypovolemia. • Feline immunodeficiency virus • Feline leukemia virus Laboratory Analysis • Feline parvovirus (panleucopenia virus) Patients with a normal physical examination and 46 TODAY’s VeTERINARY PRACTICE | November/December 2015 | tvpjournal.com SyMPTOMATIC MANAGEMENT OF PRIMARy ACUTE GASTROENTERITIS Peer Reviewed 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. When performed, laboratory testing should include a complete blood count, serum biochemical profi le, and urinalysis. Measurement of serum canine pancreas-specifi c lipase concentration may also be indicated to diagnose pancreatitis, and baseline serum cortisol concentration may be measured in order to exclude hypoadrenocorticism. Additional laboratory testing for infectious disease should be considered based on geographic location and FIGURE 1. Gastric nematode presumed to be signalment. For example, serology assists in diagnosis Physaloptera rara visualized during gastroscopy. of Salmon poisoning disease in the Pacifi c Northwest. The hemorrhage observed is associated with In dogs with diarrhea, fecal fl otation and direct smear gastric biopsy. examination should be performed to screen for primary or concurrent parasitism (Figure 1). In patients with clinical fi ndings (Table 2) or laboratory results that suggest a serious underlying cause, or those that do not respond to therapy, further diagnostic evaluation is indicated. Early identifi cation is especially important in patients requiring surgical intervention, such as those with an obstructive intestinal foreign body (Figure 2). Imaging Abdominal ultrasonography and/or abdominal Learn More radiography are strongly advised in patients Turn to page 77 to presenting with abdominal pain to screen for diseases read the article, requiring surgical intervention. It is important to Endoscopic Foreign Body Retrieval. FIGURE 2. Fabric gastric foreign body visualized TABLE 2. during gastroscopy. Selected Clinical Findings That Indicate Further Diagnostic Evaluation in Dogs & remember that pancreas-specifi c lipase concentrations Cats with Acute Vomiting and/or Diarrhea can be increased in dogs and cats with gastrointestinal • Abdominal pain foreign bodies. Therefore, it is essential to rule out • Anorexia • Bradycardia gastrointestinal foreign bodies with abdominal • Chronic vomiting or diarrhea radiographs and, possibly, abdominal ultrasound Hematemesis • before pancreatitis is diagnosed. If there is high • Hyperthermia or fever • Jaundice suspicion for a gastrointestinal foreign body that • Lack of current vaccinations may have been obscured by fl uid or gas, diagnostic • Lymphadenopathy imaging should be repeated. • Masses or organomegaly on abdominal palpation • Melena • Polyuria/polydipsia THERAPEUTIC APPROACH • Tachycardia When acute gastroenteritis is the primary cause • Tachypnea, cough, or abnormal lung sounds • Weak pulses of vomiting and/or diarrhea, the symptomatic • Weakness treatments discussed in this article are appropriate • Weight loss for therapy. However, if gastroenteritis occurs tvpjournal.com | November/December 2015 | TODAy’S VETERINARy PRACTICE 47 Peer Reviewed SYMPTOMATIC MANAGEMENT OF PRIMARY ACUTE GASTROENTERITIS secondary to an underlying disease, such as Ondansetron & Dolasetron hypoadrenocorticism, it is essential to treat the Ondansetron and dolasetron are serotonin (5-HT3) primary condition in addition to providing antagonists with potent antiemetic activity that are symptomatic and supportive therapy. commonly used off-label to control nausea in dogs This article emphasizes symptomatic treatment of and cats. This class of drug blocks the chemoreceptor primary acute gastroenteritis rather than detailing trigger zone and vagal afferent pathways involved specific treatment of serious underlying diseases that in emesis. In our experience, these drugs are very may cause similar clinical signs. effective for control of vomiting in dogs and cats. ANTIEMETIC DRUGS Maropitant For acute gastroenteritis, antiemetic therapy is often Substance P is a neurotransmitter that binds to used for the initial 24 to 48 hours when vomiting is a neurokinin-1 (NK-1) receptors and can result in prominent clinical sign (Table 3). Benefits include: vomiting. Therefore, NK-1 receptor antagonists • Improved patient comfort are powerful antiemetics effective at treating both • Decreased ongoing fluid and electrolyte losses peripheral and central causes of vomiting. • Earlier reintroduction of enteral nutrition Maropitant, a NK-1 receptor antagonist, is • Reduced risk of esophagitis and esophageal currently the only licensed antiemetic for use in dogs stricture formation. and cats and, in our opinion, is very effective. This Take care not to mask ongoing disease with drug may also have an analgesic effect and, thus, is prolonged (ie, greater than 3 days) antiemetic widely used in patients with vomiting and abdominal therapy. In addition, to reduce the risk of pain, such as those with pancreatitis.1 The efficacy gastrointestinal perforation and avoid delay of of maropitant for the control of presumed nausea is surgical intervention by masking clinical signs of controversial as some studies have shown a benefit intestinal obstruction, do not administer antiemetic while others have not documented a benefit.2-6 or prokinetic drug therapy when a foreign body is While maropitant is not licensed for IV use, we suspected or confirmed. and other clinicians have administered it by this Several classes of antiemetic drugs are used in small route—at a dose of 1 mg/kg Q 24 H—without animal medicine. Occasionally, refractory cases require the apparent adverse effects. The manufacturer use of more than one of these drugs at the same time. recommends that after 5 days of continuous TABLE 3. Medical Therapy for Vomiting Due to Acute Gastroenteritis DRUG DOGS CATS Antiemetics Ondansetron 0.1–1 mg/kg PO Q 12–24 H 0.1–1 mg/kg PO or IV Q 12–24 H Dolasetron 0.5–1 mg/kg IV Q 12 H 0.6 mg/kg IV Q 12 H Maropitant 1 mg/kg SC Q 24 H 1 mg/kg SC Q 24 H 2 mg/kg PO Q 24 H 2 mg/kg PO Q 24 H 1 mg/kg IV Q 24 Ha 1 mg/kg IV Q 24 Ha Metoclopramide 0.2 mg/kg SC or PO Q 8 H 0.2–0.4 mg/kg PO or SC Q 6–8 H 1–2 mg/kg/H IV CRI 1–2 mg/kg/H IV CRI Gastroprotectants Sucralfate 0.5–1 g PO Q 8–12 H (tablet or slurry)b 0.5 g PO Q 8–12 H (tablet or slurry)b Famotidine 1 mg/kg PO or IV Q 12 H 1 mg/kg PO or IV Q 12 H Omeprazole 1 mg/kg PO Q 12 H 1 mg/kg PO Q 12 H Pantoprazole 1 mg/kg IV Q 24 H 1 mg/kg IV