Association between echogenicity of ascites and its classification in dogs

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.

To evaluate the relationship between echogenicity of ascites and results of fluid analysis, and to determine whether echogenicity can help differentiate transudates from exudates.

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.

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.

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.