Morphological, histological and immunohistochemical changes after multiple Toxocara canis infection of lambs

Morphological, histological and immunohistochemical changes of lambs following 23 days multiple oral infections with 1,000 embryonated Toxocara canis eggs were studied up to 49 days post infection (dpi). Five-month-old Valaska lambs were divided into an experimental group (n = 18) and controls (n = 5). The small intestine, liver, lungs, brain and mesenteric lymph nodes of both infected and control lambs were examined using the routine histological methods for paraffin sections after necropsy. Two experimental lambs were killed at days 1, 3, 7, 14, 21, 28, 35, 42, and 49 (n = 2) and controls at days 14 (n = 2) and 49 (n = 3). Morphologically, a few small grey-greenish nodules on the lungs and numerous disseminated yellow-whitish nodules on the liver were found from day 21 pi to the end of experiment. Eosinophil-rich hepatic granulomas, focal T. canis-induced pulmonary inflammation, massive mononuclear and eosinophilic infiltration of the small intestine lamina propria mucosae, as well as T. canis larvae were the most prominent histological changes.Immunohistochemical examination showed the parasite in the mesenteric lymph nodes. It was concluded that multiple larval toxocarosis followed the classical migratory path in the infected lambs.