What is the recommended diagnostic approach for acute diarrhea in an otherwise stable dog?

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In a clinically stable dog with acute diarrhea, the minimum diagnostic workup is fecal flotation and a parvovirus antigen test; extensive diagnostics are of low yield and are not routinely indicated. 12 Fecal flotation is the highest-priority test. Gastrointestinal parasitism is identified in up to 22% of dogs with acute diarrhea presenting to primary care practices, even in dogs receiving routine veterinary care. 1 Fecal flotation should be performed at presentation and repeated at follow-up. 1 Parvovirus antigen testing is indicated to rule out infection before attributing diarrhea to a nonspecific cause. This is particularly important because parvovirus-positive dogs require exclusion from a stable, outpatient management pathway. 1 Abdominal ultrasound and molecular-based fecal diagnostic panels are not recommended as routine first-line tests in clinically stable dogs. Their utility in this population is questionable, and the yield does not justify routine use. 12 Extensive diagnostic testing is seldom performed in stable patients because the cause of acute diarrhea frequently remains unidentified even after thorough workup, and most cases resolve within one week regardless of etiology. 2 Fecal culture has limited diagnostic value in the absence of signs of systemic inflammation. Putative bacterial enteropathogens — including Salmonella spp., Campylobacter jejuni, Clostridium perfringens, and Clostridium difficile — are frequently isolated from healthy dogs, making positive culture results difficult to interpret clinically. 9 Fecal culture is appropriate when infectious disease is specifically suspected, not as a routine screen. 9 Biochemical evaluation is warranted when systemic or metabolic disease cannot be excluded on clinical grounds. Normal biochemical results support a primary gastrointestinal etiology and help rule out nongastrointestinal causes of diarrhea in dogs that otherwise appear stable. 1 The Dysbiosis Index (DI) is a validated PCR-based fecal ass