Comparative assessment of the most important markers of equine myopathy in connection with creatine kinase activity

Purpose: to assess the activity of AST, LDH and HBDH enzymes in relation to different levels of total creatine phosphokinase activity to understand the degree of their diagnostic value in determining the severity of myopathy in horses. Materials and methods. For the study, statistical processing of a data array of the results of a biochemical study of blood serum from 247 horses was carried out. Taking into account the reference intervals of CPK activity, all results were ranked by increasing creatine phosphokinase activity and divided into four groups. In each group, the average values for AST, LDH and HBDH were calculated, and the degree of significance of intergroup differences was calculated using the Student's t test. The correlation between the activity of the enzymes AST, LDH and HBDH with the activity of CPK in each group was also assessed. Results. An increase in the activity of creatine phosphokinase in horses by 59,4—409,6 % is accompanied by an increase in the activity of the enzymes AST by 14,5—77,2 %, LDH by 17,8—33,0 % and HBDH by 17,1—27,1 %. When comparing Pearson's correlation coefficients across the entire study sample, a significant direct relationship is determined between CPK and AST and a moderate direct relationship when comparing CPK with LDH and HBDH. Calculation of the Pearson coefficient in each of the studied groups showed different degrees of correlation between the creatine phosphokinase indicator and other enzymes, but in all cases positive. A study of the percentage contribution of HBDH to the total lactate dehydrogenase activity showed an inversely proportional relationship with respect to the activity of creatine phosphokinase, which indicates massive muscle damage with switching energy metabolism in them. Conclusion. The conducted studies made it possible to more deeply understand the cause-and-effect relationships of changes in the activity of enzymes that are specific to muscle tissue in connection with the severity of myopathy. The data obtained can assist veterinary specialists in analyzing the results of biochemical blood tests in horses.