Plasma Creatine Kinase and Aspartate Aminotransferase Activities Before, During, and After 5 Days of Intramuscular Penicillin Administration in Sedentary Horses.

This research article investigates the effects of penicillin administered intramuscularly on the levels of two enzymes (creatine kinase and aspartate aminotransferase) in the blood of horses, which can be indicators of muscle damage. Results indicate that penicillin causes a temporary increase in these enzymes, which gradually return to normal levels after treatment ends.

Study Objective and Methodology

• The aim of this research was to explore the impact of intramuscular procaine penicillin G injection on the levels of creatine kinase (CK) and aspartate aminotransferase (AST) in the plasma of horses’ blood. These enzymes are typically found inside muscle cells, and their presence in the blood can suggest muscle damage.
• The study included nine healthy adult horses, their blood was sampled for 7 days before, during the 5 days of treatment, and for 32 days after the administration of procaine penicillin G.
• The penicillin was delivered twice daily, and the blood samples were drawn daily before treatment and analyzed the same day for CK and AST activities. The statistical measures used in the study were repeated measures ANOVA and post hoc Tukey’s Test, aiming to identify any elevation of CK and AST levels compared to controls.

Results and Findings

• After the first injection of penicillin, an increase was observed in plasma CK and AST, suggesting that penicillin provoked a leakage of these intracellular enzymes into the bloodstream, indicating muscle damage.
• Plasma CK levels reached their peak after three days of treatment and returned to the reference range 9 days after the treatment began. AST levels peaked the day after the last administration of penicillin.
• The levels of AST remained elevated for longer compared to CK levels, taking approximatively 29 days after the last injection to return within the reference range in all horses.
• Overall, compared to the control period, plasma CK and AST elevations lasted for 8 and 28 days respectively after the treatment began, and for 4 and 24 days respectively after the final administration of the treatment.

Conclusion

• This study offers valuable insights into the effects of intramuscular procaine penicillin G administration on plasma CK and AST activities. The findings suggest that such treatment could cause a temporary increase in these enzymes, which are indicators of muscle damage.
• These results provide significant baseline information that veterinarians and others involved in equine health can consider when administering this kind of treatment.