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GI InTerVenTIon: PATIenT wITh AcuTe DIArrheA | Puppies and kittens, especially from shelters, are prone to viral diseases and GI parasites. Physical examination may detect: • Abdominal masses • Dilated loops of bowel • Foreign bodies • Intussusception • Abdominal pain. When patient size permits, routinely performing digital rectal palpation aids recovery of feces for observation of the presence of blood (digested [melena] or fresh) and/or mucus. Dehydration (at least 5% to be clinically noted) may be evident by dry mucous membranes, loss of skin turgor, prolonged capillary refill time, or enophthalmos. More pronounced alterations in these parameters indicate moderate dehydration (7%–9%); extreme alterations denote severe dehydration (10%–12%) approaching hypovolemic shock (tachycardia with poor peripheral perfusion and weak peripheral pulses). ACUTE DIARRHEA: DIAGNOSTICS The most important initial step in evaluating animals with acute diarrhea is to determine if they have a self-limiting or potentially life-threatening problem (Table 2). This distinction is crucial as it guides the level of diagnostics and therapy indicated, and should be based on a thorough history, careful physical examination, clinical experience and judgment, and a sound understanding of the differential diagnoses for acute diarrhea. Initial Diagnostics Fecal Flotation. Animals with suspected self-limiting diarrhea should always be tested for GI parasites by centrifugation fecal flotation using zinc sulfate, paired with indirect fluorescent antibody testing for Giardia cysts and Cryptosporidium oocysts. Cytology. Fecal cytology, a low-yield diagnostic test, is not useful for detection of potential bacterial enteropathogens (Figure). In contrast, exfoliative rectal cytology can be useful in dogs and cats with signs of colitis, especially when chronic, to identify fungal organisms or colonic neoplasia. A patient may have a potentially LIFETHREATENING PROBLEM if some of the following are present: • Moderate to severe dehydration • Abdominal pain • Depression • Melena or hematochezia • Presence of an abdominal mass or dilated loop of bowel • Frequent vomiting • Signs of systemic illness, such as: • Ascites • Lymphadenopathy • coughing • ocular and nasal discharge • hepatomegaly • oliguria/anuria • Icterus • Pyrexia If the distinction is not clear cut, it is better to be cautious and initially manage the patient as if it has a life-threatening problem. Laboratory Analysis. Measuring total plasma protein and hematocrit will help assess hydration and provide a baseline for reference if clinical signs persist or progress. Symptomatic Therapy • If dietary indiscretion has occurred, removal Figure. Photomicrograph of fecal cytolof the incriminating ogy showing sporulated organisms factors and/or feeding compatible with Clostridium perfringens. a highly digestible diet Fecal cytology, however, is not confor 3 to 5 days usually sidered to be diagnostically useful for helps resolve diarrhea. bacterial enteropathogen identification. • If parasites are detected, diarrhea should improve 2 to 3 days after appropriate treatment • If an etiology is not found, a presumptive diagnosis of acute idiopathic self-limiting diarrhea may be made. Symptomatic therapy usually relieves clinical signs in 1 to 3 days. If diarrhea persists or other clinical signs develop or intensify, a more serious problem may exist, requiring thorough evaluation and more intensive therapy. Additional Diagnostics Laboratory Analysis. Laboratory evaluation helps rank differential diagnoses as well as assess severity of dehydration and electrolyte disorders; it may include: • Complete blood count • Serum biochemistry profile • Urinalysis • Baseline cortisol (to exclude hypoadrenocorticism) • SNAP Parvo Test (idexx.com). In chronic or recurrent cases of diarrhea, serum concentrations of cobalamin and folate and canine or feline trypsin-like immunoreactivity (cTLI or fTLI) can be measured. Depending on clinical signs, patients may be evaluated for hyperthyroidism (cats) and pancreatitis. Radiography. Survey abdominal radiographs may demonstrate an abdominal mass, dilated loop of bowel, ileocolic intussusception, foreign body obstruction, or linear foreign body requiring surgical intervention. Specific Identification. Additional diagnostic tests may be indicated to definitively diagnose a specific organism or disease or to pursue diagnosis if a cause is not yet evident (eg, abdominal ultrasound). • Identification of Tritrichomonas foetus; several diagnostic tests are available • Serologic testing for feline leukemia and immunodeficiency viruses may be warranted in diarrheic cats based on housing and origin • Partial analysis for enteric pathogens, usually reserved for diarrheic pets that are systemically ill or in contact with an immunosuppressed person: » Fecal enteric panel: Gram-stained fecal smear, CPE enterotoxin enzyme-linked immunosorbent assay May/June 2013 Today's Veterinary Practice 23