Abstract: Background – Plasma nucleosome concentrations (PNC) may be used as a screening method for detecting cancer, including hemangiosarcoma, but have not been assessed in dogs with pericardial effusion (PCE). PCE is commonly caused by right atrial hemangiosarcoma (raHSA) amongst other causes. The prognosis for raHSA is grave. Hypothesis/Objectives – We hypothesized PNC would be higher in dogs with pericardial effusion due to raHSA and could subsequently serve as a screening tool for raHSA. Additionally, we proposed that PNC would be high in the effusion. Animals –Dogs with PCE due to confirmed raHSA. Methods – Dogs with PCE were evaluated and PNC was measured. Echocardiography confirmed the presence of a cardiac mass and histopathology confirmed raHSA. PNC results were classified as low risk ( < 50 ng/ml), caution zone (51 - 80 ng/ml) or high risk (> 80 ng/ml), as outlined by manufacturer’s guidelines. The upper limit of detection was 650 ng/ml. Descriptive statistics were used. Dogs with a value of >650 ng/ml were recorded at 651 ng/ml for statistical purposes. The false negative rate (FNR) and true positive rate (TPR) for plasma was calculated using low risk and high risk. Results – The median PNC was 102.1 ng/ml (22.6 to 651). Four dogs were classified as low risk, three dogs were in the caution zone, and eight dogs were at high risk. FNR was 33% and TPR was 67%. PCE was evaluated in 8/15 dogs, with seven having PNC of 651 ng/ml, and one having PNC of 47.7 ng/ml. Conclusions and Clinical Importance – PNC in dogs with documented raHSA are variable, and low PNC do not exclude raHSA.
