Evaluation of a handheld device for the measurement of beta-hydroxybutyrate in capillary blood obtained by the puncture of the vulva as well as in venous whole blood in cattle.

A negative energy balance is a common condition in high yielding dairy cows causing the production of ketone bodies (KB), including beta-hydroxybutyrate (BHB), defined as subclinical ketosis (SCK) if clinical signs are missing. The aim of the present study was to evaluate a handheld electronic device for the detection of SCK (BHB-concentration > 1.2 mmol/l), in capillary blood and venous whole blood in cows (WellionVet BELUA, MED TRUST Handels GmbH, Marz, Austria) as well as the feasibility of the puncture of the external vulva with a single use lancet. For this purpose, the blood BHB-concentration was tested in 250 venous and capillary blood samples and compared to the results of a certified laboratory. The majority (76.3%) of the animals displayed no signs of discomfort related to the puncture and in 74.2% the procedure was successful on the first attempt. The BHB-concentrations detected in capillary blood showed good agreement with the reference method, both in capillary (correlation coefficient 0.94 (p⟨0.001), Kappa-value 0.89) and venous whole blood (correlation coefficient of 0.95 (p⟨0.001), Kappa-value 0.89). Altogether, 98% of all the samples were correctly classified as SCK or non-SCK by the handheld device in capillary blood (sensitivity 0.96, specificity 0.98) and 97.4% in venous whole blood (sensitivity 0.889, specificity 0.991), respectively. An increase in the correlation by the adaptation of the cut off level could not be achieved for both sampling sites.