A prospective cohort study of C‐reactive protein as a marker of aspiration pneumonia in canine tick paralysis (Ixodes holocyclus)

Objective To evaluate the diagnostic and prognostic utility of C‐reactive protein (CRP) in dogs with tick paralysis, focusing on its relationship with thoracic radiographic severity scores (TRSS). Methods Twenty client‐owned dogs presenting to a veterinary emergency hospital were enrolled. CRP concentrations, TRSS, white blood cell count, red blood cell count, vital signs and oxygenation indices were assessed for up to 72 hours from admission. Results Using a CRP cut‐off of ≥20 mg/L, sensitivity and specificity estimates for detecting pneumonia were both 0.86 but imprecise (95% confidence interval [CI] 0.49–0.99, 95% CI 0.57–0.98 respectively). CRP was moderately correlated with TRSS (Spearman's ρ = 0.77, 95% CI 0.60–0.88, P < 0.001) and was negatively correlated with heart rate (r = −0.302, 95% CI −0.518 to −0.049, P = 0.02), SpO 2 (r = −0.342, 95% CI −0.550 to −0.094, P = 0.008) and the SpO2/FiO 2 ratio (r = −0.292, 95% CI −0.510 to −0.039, P = 0.025). TRSS was negatively correlated with total WBC count (ρ = −0.382, 95% CI −0.638 to −0.051, P = 0.026). There was no evidence that CRP differs by gait score or respiratory grade after accounting for TRSS. Temporal trends by case showed that CRP increases in parallel with worsening radiographic scores. Conclusions CRP is a valuable biomarker for pneumonia in dogs with tick paralysis in conjunction with other clinical indicators of pneumonia.