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Story: Diseases of sheep, cattle and deer

Internal parasites of sheep

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Internal parasites of sheep

Roundworms, tape worms and flukes are all internal parasites of sheep. Roundworms, or nematodes, are of most concern, and there are 29 species in New Zealand. They are estimated to cost about $300 million per year in lost production and drench use. Adult roundworms live in the sheep’s gut and produce eggs, which are passed out with dung onto pasture. Over the next few days to several weeks, depending on moisture and temperature, the eggs hatch and develop through three larval stages. The larvae climb up moist grass and are eaten by grazing sheep.

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Te Ara - The Encyclopedia of New Zealand

Source: D. M. West, A. N. Bruere, and A. L. Ridler, The sheep: health, disease and production. 2nd ed. Palmerston North: Veterinary Continuing Education, Massey University, 2002, fig 8.1

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How to cite this page

Gary Clark, Neville Grace and Ken Drew, Diseases of sheep, cattle and deer – Sheep contagious diseases, Te Ara – the Encyclopedia of New Zealand, https://teara.govt.nz/en/diagram/17431/internal-parasites-of-sheep (accessed 11 June 2026).

Story by Gary Clark, Neville Grace and Ken Drew, published 1 March 2009.