Association between echogenicity of ascites and its classification in dogs.

Background: Ascites in dogs results from a range of systemic and localized disorders. Early distinction between transudative and exudative peritoneal effusions, and between septic and non-septic exudates, is crucial for guiding emergency interventions and treatment strategies. Objective: To evaluate the relationship between echogenicity of ascites and results of fluid analysis, and to determine whether echogenicity can help differentiate transudates from exudates. Methods: Retrospective study including 100 client-owned dogs with ultrasonographically confirmed peritoneal effusion and fluid analysis performed within 3 h of imaging. Effusions were classified according to total nucleated cell count (TNCC) and total protein concentration (TPC) as follows: transudates (<1,500 cells/μL, <2.5 g/dl), exudates (≥5,000 cells/μL, ≥2.5 g/dl), or other (hemoperitoneum, biliary peritonitis, uroperitoneum). Static DICOM images and cine loops were acquired and independently assessed by a board-certified radiologist and a radiology resident. Consensus was reached for all cases. Effusions with uniform echo-free appearance were deemed anechogenic; those containing multiple or confluent hyperechoic foci were classified as echogenic. Results: Sixty-six effusions were echogenic and 34 anechogenic. Of the 40 exudates, 80% were echogenic compared to 43% of the 41 transudates. All 17 septic exudates (100%) were echogenic compared to 65% of 23 non-septic exudates. TNCC (≥5,000 cells/μL) and TPC (>4.5 g/dL) were strongly correlated with echogenic appearance. Conclusions: Echogenicity correlated significantly with exudative and septic effusions. Echogenicity may offer a rapid, non-invasive method to complement cytologic and biochemical analyses. Incorporating echogenicity assessment into abdominal ultrasonographic protocols may hasten critical clinical decision-making and improve outcomes in dogs with ascites.