Effects of Anticoccidial Drugs on Gross and Histopathological Lesions Caused by Experimental Rabbit Coccidiosis

Abstract

Effects of commonly used anticoccidial drugs in treating lesions caused by intestinal and hepatic coccidiosis have not been described for anticoccidial-drugs used in Kenya. The objective of this study was to describe the effects of four anticoccidial drugs on gross and histopathological lesions caused by artificially-induced mixed Eimeria infection with inoculant dose of E. flavescens (20%), E. perforans (21%), E. intestinalis (9%), E. coecicola (4.2%), E. media (11.2%), E. piriformis (10.6%), E. stidae (16%), and E. Magna (8%). In a controlled laboratory trial, 60 weaner rabbits were randomly allocated to treatment groups A, B, C, D, E and F. Each group had 10 rabbits. Groups A and C served as uninfected-untreated and infected-untreated control groups, respectively. Groups B, D, E and F were experimentally infected and treated with amprolium, diclazuril, sulfachloropyrazine, and trimethoprim-sulfamethoxazole, respectively. On day 30 post treatment, 3 rabbits from each treatment group were selected randomly and humanely euthanized for gross and microscopic lesion examination. Diclazuril and sulfachloropyrazine treatment groups had significantly minimal to no macroscopic and microscopic lesions. This was consistent with a high efficacy of the drugs in reversing intestinal and hepatic lesions of coccidiosis in rabbits. Rabbits from amprolium, trimethoprim-sulfamethoxazole and infected-untreated control groups presented with severe intestinal and hepatic gross lesions characterized by extensive hepatomegaly, numerous raised hepatic multinodular lesions and marked congestion of the intestines that indicated mild to no effect of the drugs in reversing hepatic and intestinal lesions. Microscopic lesions in rabbits treated with amprolium and trimethoprim-sulfamethoxazole had marked desquamation of intestinal and bile duct epithelium, distended and thickened bile duct, numerous coccidian parasites at different stages of development in duct epithelium and mature oocysts in the intestinal and bile duct lumens; as was in positive control group. Additionally, rabbits from the three treatment groups recorded higher intestinal and hepatic histological lesion scores.