Fecundity and proglottid release of Taenia ovis and T. hydatigena

The rate of release of proglottids was examined in 19 dogs infected with Taenia ovis and 16 infected with T. hydatigena. Faeces were examined for proglottids daily until the apparent death of the worms. Autopsies were then performed and surviving worms recovered. The number of eggs per proglottid was estimated in 12 T. ovis and 12 T. hydatigena from natural infections. In dogs infected with T ovis the time of first recovery of proglottids after infection varied from 44 days to more than 126 days. Up to 3 proglottids per worm per day might be released, each containing about 88,000 eggs. Infection can persist longer than 5 years. Dogs infected with T. hydatigena released their first proglottid from 48 to 65 days after infection. Each worm could produce 2 proglottids per day, each containing about 53,000 eggs. Although each T. ovis may produce over 250,000 and each T hydatigena over 100,000 eggs per day, it is probable that many of them hatch in the small intestine and are rendered inactive.