Larval toxocarosis in sheep: the immunohistochemical characterization of lesions in some affected organs.

Morphological and immunohistochemical responses of lambs following oral infection with 10,000 infective Toxocara canis (T. canis) eggs were studied up to 28 days post-infection (pi). The small intestine, liver, lungs and brain of both infected and control lambs were examined using the routine histological methods for paraffin sections and immunohistochemical techniques for frozen tissue sections. Eosinophil-rich hepatic granulomas and diffuse T. canis-induced pulmonary inflammation were the most prominent pathological features. CD2+, CD4+, CD8+, IgM bearing cells, and macrophages were demonstrated in the liver granulomas. The observed histomorphologic changes were similar to other paratenic hosts. It was concluded that larval toxocarosis followed the classical migratory path in the infected lambs.