Physiological and biochemical assessment of markers of renal pathology in tigers at different age periods

Objective: to study the relationship between biochemical blood markers in tigers and to determine age-related predisposition to impaired renal filtration capacity. Materials and methods. To achieve this goal, the results of a biochemical blood test from tigers (N=41) aged from two months to 18 years were statistically analyzed. The tigers belong to various organizations: zoos, nurseries, circuses, and the "Tiger House" hospice. The blood test was conducted using "Randox" test systems. The results of creatinine, urea, inorganic phosphorus, potassium, and creatine kinase determination were used in this study. The biochemical test results were divided into 5 groups based on age. For statistical processing of the results, the Microsoft Excel software package was used, in which the functions of data grouping, calculation of the mean value (M), error of the mean (m), determination of the variation coefficient and the correlation coefficient were performed. Results. A progressive increase in creatinine concentration in age dynamics from 83,6 ± 16,1 μmol / l to 637,9 ± 224,3 μmol / l was revealed. A unidirectional increase in the level of creatinine and urea in tigers aged from 7 to 18 years was determined, at a young age, the concentration of urea almost does not change and ranges from 9,91 ± 0,83 mmol / l to 11,62 ± 1,67 mmol / l. The change in the concentration of inorganic phosphorus in connection with age can be illustrated by a parabolic curve with the lowest value corresponding to the age period of 3—6 years. No significant age-related fluctuations in serum potassium concentration were found in tigers; the differences between the lowest and highest values were 9,5 %. Blood creatine kinase activity did not show any significant changes up to the age of 12; only in the oldest age group of 14—18 years did the enzyme activity increase by 5,3 times. A wide range of creatinine concentrations was observed in all age groups; the variation coefficient ranged from 27,7 % to 89,8 %. An examination of the correlation coefficients when comparing creatinine concentration with other parameters revealed a close positive relationship with urea both in the entire sample and in the age range from 7 to 18 years. No significant correlation relationships were found for potassium. Conclusion. Blood creatinine levels in tigers in all age groups are subject to significant fluctuations, and this is a reason to substantiate objective reference intervals for these animals. The concentration of creatinine in the blood of tigers increases progressively with age. At a young age, this trend is not directly related to the deterioration of the filtration function of the kidneys, since up to 6 years of age, animals do not show a parallel increase in the concentration of urea and inorganic phosphate. In the older age period from 7 to 18 years, tigers show a predisposition to kidney diseases, since along with an increase in creatinine in the blood, there is an increase in the concentration of urea (r = 0,929) and inorganic phosphate (r = 0,687).