Dose-dependent egg excretion in foxes ( Vulpes vulpes) after a single infection with Toxocara canis eggs

Faecal egg counts were performed daily for a period of 4 months on six silver fox cubs inoculated individually with an egg dose of 30, 100, 300, 1,000, 3,000, or 20,000 Toxocara canis eggs. At the lowest and the highest dose levels, the cubs did not develop patent infections. In the remaining cubs, the initial appearance of eggs in the faeces occurred 35-38 days post-infection (DPI), the patency period varied between 8 and 72 days, and the maximal EPG ranged from 980 to 5,700 (39-85 DPI). The highest egg excretion rates were found in cubs inoculated with 300 and 1,000 eggs. This study demonstrates that T. canis egg excretion rate in fox cubs is not linearly correlated with the ingestion level.