Urinary 11‐dehydrothromboxane B2 concentrations in 20 dogs with primary immune‐mediated hemolytic anemia

Abstract Background Thromboembolic disease is a major cause of mortality in dogs with immune‐mediated hemolytic anemia (IMHA). At present, no reliable biomarkers of individual patient thrombotic risk are available. In human medicine, increased urinary thromboxane concentrations have utility as markers of prothrombotic tendency in various situations. Hypothesis/Objectives First, to determine if urinary 11‐dehydrothromboxane B2 (u11‐dTXB) concentrations are increased in dogs with primary IMHA compared to normal dogs; second, to assess whether u11‐dTXB concentration is associated with survival, known prognostic indicators, or frequency of thrombosis in dogs with IMHA. Animals Twenty client‐owned dogs diagnosed with primary IMHA and 17 healthy dogs volunteered by hospital staff. Methods Prospective case‐control study. A previously validated ELISA was used to measure urine 11‐dTXB concentrations, which were normalized to urine creatinine concentration (u11‐dTXB:Cr). Samples were obtained at presentation from patients with primary IMHA. Standard clincopathological data at baseline and survival data were collected. Urinary 11‐dTXB:Cr was compared between outcome subgroups, and correlated with known markers of disease severity. Results Baseline u11‐dTXB:Cr was significantly higher in dogs with IMHA than in healthy dogs (median, 3.75; range, 0.83‐25.36 vs 0.65; 0.24‐2.57; P = .003) but did not differ between dogs with IMHA that survived and did not survive to 30 days after presentation, nor between dogs with and without clinical suspicion of thrombotic disease. Conclusions and Clinical Importance Urinary 11‐dTXB:Cr is increased in dogs with IMHA compared to healthy controls, consistent with a prothrombotic state. However, in this IMHA population u11‐dTXB:Cr was not associated with survival or suspected thrombosis.