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.