Department of Internal Diseases, Faculty of Veterinary Medicine, Trakia University, 6000 Stara Zagora, Bulgaria
(Manuscript received 29 November 2022; accepted for publication 22 May 2023)
Abstract. The purpose of the present study was to establish the biochemical and pathohistological changes in Holstein cows with subclinical and clinical form of ketosis. A total of 47 Holstein cows from 1st to 4th lactation were included in the study. Blood samples were obtained from all animals for determination of β-hydroxybutyrate (ВНВА, mmol/l), non-esterified fatty acids (NEFA, mmol/l), glucose (Gl, mmol/l), aspartate aminotransferase (ASAT, U/l), alanine aminotransferase (ALAT, U/l) and total bilirubin (Tb, µmol/l). The cows were divided into three groups depending on their physiological condition: pregnant, recently calved and lactating. The cows from the three groups were classified as healthy (control, n=24, BHBA<1.2 mmol/L), affected with subclinical ketosis (SCK, n=15, BHBA from 1.2 to 2.6 mmol/l) and with clinical ketosis (CK, n=8, BHBA>2.6 mmol/l) depending on their blood BHBA levels. The pathohistological investigations were done after autopsy of cows diagnosed with clinical ketosis. The blood levels of NEFA in cows of the three groups with SCK were statistically significantly elevated vs control groups, while in cows with CK – decreased, vs both controls and SCK. The levels of glucose decreased, while the activities of ASAT, ALAT and Tb levels were increased in cows with SCK and CK ketosis vs controls. Histological studies revealed karyolysis, karyorrhexis, cellular vacuolation in hepatocytes, as well as necrotic changes and fatty dystrophy of the liver and kidneys in cows with clinical ketosis.