Serum C-reactive protein (CRP) is widely used to assess inflammatory disease progression and treatment response in dogs. High-dose glucocorticoids are a common therapy for such conditions, but their independent effect on CRP is not well understood. This study measured CRP using two immunoassays—sandwich ELISA and particle-enhanced turbidimetric immunoassay—in 12 healthy beagle dogs treated with either oral hydrocortisone (8 mg/kg every 12 hours) or a placebo over 28 days, with samples collected on days 0, 1, 5, and 28. Minor fluctuations in CRP occurred in both groups, and no significant effect of hydrocortisone was observed (p = 0.761). On day 28, CRP decreased by more than 2.7-fold in three dogs receiving hydrocortisone and two placebo dogs, while one placebo dog showed a similar increase. These results suggest that high-dose hydrocortisone does not confound CRP measurement in healthy dogs, supporting CRP as a reliable biomarker for monitoring inflammation. Future studies should explore potential cellular effects of corticosteroids, including hepatic protein and transcriptome changes.
