Serum C-reactive protein and haptoglobin decrease in the first three months of treatment and relative change in haptoglobin predict remission in dogs with pulmonary coccidioidomycosis

OBJECTIVE To evaluate temporal changes in serum C-reactive protein (CRP) and haptoglobin (Hp) concentrations in dogs with pulmonary coccidioidomycosis and assess their utility to detect remission. METHODS 31 client-owned dogs with newly diagnosed pulmonary coccidioidomycosis from October 2020 to February 2021 were included in a retrospective cohort study that utilized archived serum. Serum was originally obtained at diagnosis and once every 3 months after antifungal administration until either remission or 12 months. Time points were designated as baseline (T0), 3 months (T1), 6 months (T2), 9 months (T3), and 12 months (T4). Serum CRP and Hp were measured at a reference laboratory with ELISA assays. RESULTS Median serum CRP and Hp concentrations decreased from T0 (CRP, 56 mg/L; Hp, 716.1 mg/dL) to T1 (CRP, 3.3 mg/L; Hp, 240.5 mg/dL); subsequent decreases were not significant. Eighteen (60%) and 16 (53%) of 30 dogs had normal serum CRP and Hp concentrations at T1, respectively. Absolute serum CRP (AUC, 0.58; 95% CI, 0.45 to 0.72) and Hp (AUC, 0.65; 95% CI, 0.52 to 0.78) were poor detectors of remission. However, the percentage change in Hp from T0 to T1 (AUC, 0.90; 95% CI, 0.74 to 1.0) was an excellent predictor of remission within 12 months. CONCLUSIONS Serum CRP and Hp concentrations decrease in the first 3 months of antifungal treatment in dogs with pulmonary coccidioidomycosis, and the percentage change of Hp may help predict dogs that will achieve remission within 12 months of treatment. CLINICAL RELEVANCE Serum CRP and Hp may be useful adjunctive biomarkers to monitor treatment response in dogs with pulmonary coccidioidomycosis.