Histopathological and Biochemical Characterization of Hepatic Lipidosis in Dairy Cows: Correlation with Subclinical Ketosis

During the periparturient period, high-yielding dairy cows frequently develop metabolic disorders, notably subclinical ketosis (SCK) and hepatic lipidosis (fatty liver), both arising from negative energy balance and excessive adipose tissue mobilization. This cross-sectional study aimed to describe the histological and biochemical features of hepatic lipidosis, investigate its association with SCK, and evaluate the diagnostic utility of selected biomarkers for detecting moderate-to-severe hepatic lipidosis in early-lactation cows. A total of 250 Holstein-Friesian dairy cows were enrolled within the first four weeks postpartum. Liver biopsies were obtained for histological grading of hepatic lipidosis, and blood samples were analyzed for BHB, NEFA, glucose, AST, GLDH, and triglycerides. Results showed that 42.0% (n=105) of cows had SCK (BHB ≥ 1.2 mmol/L), while 32.8% (n=82) had moderate-to-severe hepatic lipidosis (≥5% fat). A significant positive correlation was found between the severity of hepatic lipidosis and SCK (Spearman's ρ = 0.62, p < 0.001). Cows with severe hepatic lipidosis exhibited significantly lower glucose and triglycerides, alongside markedly higher BHB, NEFA, and AST compared to cows with mild lipidosis. Notably, the combined BHB-AST biomarker panel demonstrated outstanding diagnostic accuracy for detecting moderate-to-severe hepatic lipidosis (AUC = 0.92, 95% CI: 0.88–0.96). Cows concurrently affected by SCK and moderate-to-severe hepatic lipidosis had significantly longer days to conception and a 3.2-fold higher risk of secondary diseases. In conclusion, while hepatic lipidosis and SCK are closely interrelated, their association is not absolute. The BHB-AST panel offers superior diagnostic performance for identifying severe hepatic lipidosis. Cows with concurrent conditions represent a high-risk group requiring close monitoring and targeted management. These findings support implementing routine biochemical screening programs in transition dairy herds to detect at-risk animals and improve both health and reproductive outcomes.