Development and clinical evaluation of a quantitative fluorescent immunoassay for detecting canine CRP

Canine C-reactive protein (cCRP) is one of the major positive acute phase proteins in dogs and is commonly measured to detect and monitor systemic inflammation as well as the efficacy of treatment. Traditional methods for testing cCPR, including enzyme-linked immunosorbent assay (ELISA), have some drawbacks, such as a long time for diagnosis and the requirement of well-equipped laboratories. Therefore, there is a need for a rapid and precise diagnostic test for cCRP at point-of-care. This study assessed the accuracy, precision, and validated clinical effectiveness of a diagnostic test based on fluorescent lateral flow immunoassay to detect cCRP. For the standard cCRP concentration ranging from 0 to 200 μg/mL, the cCRP diagnostic test showed strong linearity with R² of 0.9977 (p < 0.001), and both inter- and intra-assay CVs were <14%. The limit of detection and limit of quantitation were found to be 4.0 μg/mL and 5.0 μg/mL, respectively. The cCRP serum concentration was evaluated in 21 client-owned dogs and the results were compared to a previously validated ELISA. The Pearson Correlation Coefficient between the diagnostic test kit and ELISA was 0.942 [95% confidence interval: 0.859 to 0.976, p < 0.001], and the Bland-Altman plot indicated a bias of 26.82% [95% limits of agreement: -56.03 to 109.67], indicating a significant correlation and the agreement between the data from the cCRP diagnostic test and ELISA. In conclusion, the fluorescent immunoassay based diagnostic test is a suitable option for rapidly and precisely detecting cCRP in dogs, providing a convenient alternative to traditional methods for diagnosing acute inflammation.