Point-of-care troponin I assay has acceptable performance detecting clinically important canine myocardial injury but reduced precision at low concentrations

Objective: To perform a partial validation of a point-of-care assay (Vcheck cardiac troponin I [VC-cTnI; cTnI]) for measurement of cTnI in canine serum and to perform a method comparison between the VC-cTnI and an established chemiluminescent assay (ADVIA Centaur XP High-Sensitivity Troponin I [AC-cTnI-HS]). Methods: From September 4, 2024, through August 21, 2025, surplus canine serum was collected from a diagnostic laboratory, and within-day variability, dilutional parallelism, spiking recovery, and the effect of common interferents (hemolysis, icterus, and lipemia) were analyzed for the VC-cTnI assay. A method comparison of the VC-cTnI and AC-cTnI-HS assays was performed with 121 canine serum samples. Results: The within-day coefficient of variation ranged from 8.1% to 43.8%, decreasing as cTnI concentrations increased. Dilutional parallelism and spiking recovery assessments had mean ± SD observed-to-expected ratios of 80.5 ± 33.2% (range, 21.1% to 122.2%) and 112.8 ± 35.6% (range, 46.0% to 173.9%), respectively. There was no interference from icterus, hemolysis, or lipemia. There was a positive correlation between the VC-cTnI and AC-cTnI-HS assays (Spearman ρ, 0.742), though 16 of 121 samples (13.2%) were below the VC-cTnI detectable limit. Conclusions: The VC-cTnI assay lacked precision for measurement of concentrations below 0.2 ng/mL, but within-day variability was acceptable for higher concentrations. Clinical Relevance: The VC-cTnI assay is more precise when measuring higher cTnI concentrations and can detect myocardial injury in dogs. Results in the normal and equivocal range of the manufacturer's reference interval may be more challenging to interpret because of suboptimal precision in this range.