Diabetic ketoacidosis (DKA) is a life-threatening complication of diabetes mellitus (DM). The standard method of detection of ketone bodies is the dipstick method, which detects semiquantitatively acetoacetate, but not β-hydroxybutyrate (β-HB). The objectives of the current study were to assess the diagnostic utility of β-HB to diagnose diabetic ketosis (DK) and DKA in cats and to establish a cut-off value for the diagnosis of DKA. Sixty-two cats were included in the study. Eleven cats were healthy (group 1); in the remainder of cats (51), a diagnosis of DM was based on hyperglycemia, glucosuria, and increased fructosamine concentrations. Nineteen of 51 cats suffered from nonketotic diabetes mellitus (group 2). In 11 cats, plasma ketone bodies were detected with the dipstick method (diabetic ketosis, group 3). In 21 cats, plasma ketone bodies and metabolic acidosis were present (DKA, group 4). Plasma β-HB was measured in all cats by an enzymatic method (spectrophotometry). A cut-off value for the diagnosis of DKA was calculated based on the receiver operating characteristic curve. In healthy cats, the β-HB concentration ranged from 0 to 0.1 mmol/l; in cats of group 2, from 0 to 0.9 mmol/l (median: 0.1 mmol/l); in cats of group 3, from 0.6 to 6.8 mmol/l (median: 1.7 mmol/l); and in cats of group 4, from 3.8 to 12.2 mmol/l (median: 7.9 mmol/l). A cut-off value of 2.4 mmol/l revealed 100% sensitivity and 87% specificity to diagnose DKA. Beta-hydroxybutyrate is a useful parameter for the diagnosis of diabetic ketosis and DKA in cats.
