Bacterial peritonitis, a life-threatening condition that requires extensive treatment, is most often diagnosed from cytology of the abdominal effusion. Identification of intracellular bacteria in the abdominal effusion confirms a diagnosis. A positive bacterial culture can also confirm the diagnosis, but culture results may take 5 to 7 days. In human medicine, studies have shown that the Multistix 8 SG Reagent Strip (Bayer Diagnostics) can be useful for prediction of bacterial peritonitis with high specificity.
The Multistix 8 SG Reagent Strip sensitivity and specificity in the diagnosis of bacterial peritonitis in dogs with free abdominal fluid was evaluated in this study. All 60 dogs presented with free abdominal fluid. For each dog, a drop of fluid was applied to the leukocyte esterase test pad on the reagent strip; fluid was also submitted for cytology and culture. Effusions were classified as nonseptic exudates (n = 7), neoplastic effusions (n = 6), modified transudates (n = 25), pure transudates (n = 10), and septic exudates (n = 12). The dipstick was found to have a sensitivity of ~60% to 75%, specificity of ~91% to 92%, a positive predictive value of ~69%, and a negative predictive value of ~87% to 94%. The authors conclude that a negative dipstick test result may guide the clinician to considering alternative diagnoses in dogs with free abdominal effusion.