Diagnosis of subclinical ketosis in dairy cows

Ketosis is a common disease in high producing dairy cows during the early lactation period. Subclinical ketosis (SCK) and periparturient diseases considerably account for economic and welfare losses in dairy cows. Subclinical ketosis poses an increased risk of production-related diseases such as clinical ketosis, displaced abomasum, retained placenta, lameness, mastitis and metritis. Production efficiency decreases (lower milk production, poor fertility, and increased culling rates), which results in economic losses. Increased concentrations of circulating ketone bodies, predominantly β-hydroxybutyrate (BHB), without the presence of clinical signs of ketosis are considered as SCK. It is characterized by increased levels of ketone bodies in the blood, urine and milk. The gold standard test for ketosis is blood BHB. This ketone body is more stable in blood than acetone or acetoacetate. The most commonly used cut-points for subclinical ketosis are 1.2 mmol/L or 1.4 mmol/L for BHB in the blood. Clinical ketosis generally involves much higher levels of BHB, about 3.0 mmol/L or more. Usually, detection of SCK is carried out by testing ketone body concentrations in blood, urine and milk. A variety of laboratory and cowside tests are available for monitoring ketosis in dairy herds.Butno cowside test has perfect sensitivity and specificity compared to blood BHB as the gold standard test. The aim of this review is to overview diagnostic tests for SCK in dairy cows, including laboratory and cowside tests.