Evaluation of Hepatic Function in Foals with Rhodococcosis after Treatment with Azithromycin and Rifampin

This study was carried out to evaluate the effect of two antimicrobials, (azithromycin and rifampin), on Rhodococcosis, a foal disease caused by Rhodococcus equi and to evaluate potential effects of the treatment on foals’ hepatic function. This study was conducted on 17 infected 2-15 months old foals, while 18 healthy foals were kept as control. Rhodococcosis in foals was confirmed by clinical signs and laboratory findings. In order to assess hepatic function the following enzymes were measured in serum of foals: Gama Glutamine Transferase (GGT), Aspartate Aminotransferase (AST), Alanin Aminotransferase (ALT), Alkalin Phosphatase (ALP) and Bilirubin (BIL). For treatment, azithromycin in combination with rifampin orally once a day for 2 weeks were used. At the end of the treatment, clinical symptoms resolved; however, it was observed intestinal disorders in the 13 foals. Among infected foals, serum markers of liver damage increased. Mean serum activity of GGT, AST and ALT was (P<.05) significantly higher among infected foals before treatment than among control foals, while the infected foals and mean difference between control and infected after treatment was not significant (P>.05). Serum activity of ALP in the diseased foal had a significant increase and mean difference between all three groups was significant (P<.05). Though mean serum levels of total BIL among sick foals was significantly (P<.05) lower than before treatment, it was significantly (P<.05) higher than control, and despite decreased, after treatment compared to before treatment, but not to normal and mean difference between 3 groups was significant (P<.05).
The findings of this study indicate that azithromycin in combination with rifampin was effective in the treatment of foals with bronchopneumonia by R. equi. Additionally, no adverse effects were noticeable on hepatic function.