MVSc

The present research was designed and conducted with the objectives of assessing the normal serum activity of hepatobiliary enzymes such as, ALT, AST, ALP and GGT for different animal species reared under the hot humid climatic conditions and to identify the ideal storage condition for each enzyme in these species by keeping sera samples at room temperature, 4 ºC and -20 ºC up to 14 days. The study was performed in adult healthy female crossbred cattle, Murrah buffalo and crossbred goats maintained at University Livestock Farms, College of Veterinary and Animal sciences, Mannuthy and dogs of mixed breeds maintained at nearby kennels during the period of April to October 2008.

The research findings showed highest ALT activity in buffalo (50.00 ± 3.53 IU/L) followed by dog (33.56 ± 3.38 IU/L) and comparatively lower ALT activity in cattle and goat serum where the values were 19.46 ± 1.54 and 15.94 ± 0.84 IU/L, respectively. The reference range obtained for ALT activity in cattle, buffalo, goat and dog were of 16.11 to 22.81, 42.02 to 57.98, 14.17 to 17.72 and 25.15 to 41.36 IU/L, respectively. These results recommend the use of ALT assay particularly in dogs and buffalo for the diagnosis of hepatic damage. All the four species showed significant differences in the mean AST activities with highest activity for buffalo serum (113.53 to 146.49 IU/L) and lowest for dog (30.53 to 41.31 IU/L) with a reference range of 113.51 to 146.49 and 30.35 to 41.31 IU/L, respectively. For cattle and goat sera samples, the AST activity observed were 68.67 ± 2.29 IU/L (63.61 to 73.72) and 80.87 ± 3.71 IU/L (72.89 to 88.84), respectively.

The analysis showed comparatively wider range for ALP activity in all the four species studied as referred to other hepatobiliary enzymes. The highest ALP activity was found in buffalo (323.60 ± 32.09 IU/L) ranging from 251.00 to 396.19 IU/L. The mean serum ALP activities for cattle and dog were 113.70 ± 7.59 IU/L (96.53 to 130.87) and 92.90 ± 7.53 IU/L (75.87 to 109.93) and were non significant. The ALP values obtained for goat was 175.92 ± 20.09 IU/L (131.71 to 220.13 IU/L). GGT levels obtained in the present study were within a narrow range in all the animals studied. The highest serum GGT activity was found in goats (32.57 ± 1.73 IU/L) and the lowest value in dogs (4.00 ± 0.15 IU/L) with a range of 31.41 to 39.13 and 3.66 to 4.34, respectively. The serum GGT activity of cattle and buffalo were found to be some what similar (13.15 ± 0.78 and 10.11 ± 1.28 IU/L, respectively). The corresponding reference ranges were 11.45 to 14.86 and 7.15 to 13.07, respectively. The results suggest GGT as the most suitable hepatobiliary enzyme than ALP to detect cholestasis in all the four species studied.

The present study also reveals significant differences in the storage stability characteristics of the hepatobiliary enzyme among the four species. The investigation recommends 4 ºC as the ideal storage condition for ALT assay for cattle and dog serum samples, whereas, -20 ºC for goat serum and both conditions for buffalo serum. Both 4 ºC and -20 ºC was suitable for AST assay for cattle and dog serum, -20 ºC is recommended for goat whereas, buffalo serum showed maximum AST stability at 4 ºC. The present study suggests that ALP assay should be performed on the day of venipuncture itself in all four species studied as the enzyme showed wide variation upon storage. Both 4 ºC and -20 ºC was found to be as the ideal storage conditions for GGT assay in buffalo, goat and dog sera samples whereas, 4 ºC is recommended for cattle serum where the observed stability period was 11 days. Room temperature is not recommended for preserving sera samples for enzyme assay in all the four species except for GGT estimation in goat and dog serum where the enzyme was found to be stable up to the end of the study period. These differences in enzyme stability should be considered while preserving sera samples to get an accurate result.