Internal parasites pose a significant health threat to sheep, particularly in warm, moist climates, with increasing resistance to traditional dewormers necessitating an integrated management approach. Sheep and lamb susceptibility varies, demanding strategies like pasture rotation, multi-species grazing, and genetic selection for parasite resistance to mitigate infestations. Future developments in treatments and vaccines are underway, including natural anthelmintics and new drugs, highlighting the need for ongoing research and adaptation in parasite control methods.

1. Internal parasite control in sheepSUSAN SCHOENIAN (Shāy-nē-ŭn)Sheep & Goat SpecialistWestern Maryland Research & Education Centersschoen@umd.edu - www.sheepandgoat.com

2. Internal parasites: the realitiesInternal parasites are the primary health problem affecting sheep in warm, moist climates.Except for goats, sheep are the most susceptible farm livestock to internal parasites.Though it varies by geographic location and individual farm, worms are rapidly developing resistance to the anthelmintics.Nowadays, successful worm control requires an integrated approach that does not rely solely on anthelmintics.Anthelmintic = dewormer

3. What is a parasite?A (generally undesirable) living organism that exists by stealing the resources produced or collected by another living organismSource: Wiktionary

4. There are two kinds of parasites.Internal (endo) - a parasite that lives inside another organism.External (ecto) - a parasite that lives on the blood of the host or lays eggs on their hide or in their nose.

5. There are two general kinds of internal parasites.Parasites “tend” to be species-specific.1) Helminths (multi-cellular)Nematodes (roundworms)Cestodes (tapeworms)Trematodes (flukes)2) Protozoa (single cell)CoccidiaGiardiaCryptospordium

6. HELMINTHSNematodes (roundworms)Over 20,000 species

7. Long

8. Round

9. Not segmented

10. Microscopic

11. Sexual reproduction

12. Male and female worms

13. Haemonchus contortus Barber pole wormScour wormsTrichostrongylus spp. Hair worm

14. Teladorsagia Brown stomach wormOesophagostomum Nodule wormNematodirus spp. ThreadwormOtherLungworms

15. Meningeal wormNEMATODEBlood sucker

16. Found in abomasum

17. Most pathogenic

18. Causes anemia, bottle jaw, and death.

19. Prolific egg producer

20. Direct life cycle

21. Requires warmth (60°F) and moisture to complete its life cycle

22. Short 3 week life cycleBarber pole wormHaemonchus contortus

23. NEMATODESFound in abomasum and Intestines.

24. Usually found in mixed infections with barber pole worm.

25. Not as pathogenic as barber pole worm.

26. Cause digestive problems (scouring) and ill thrift.

27. Similar life cycle and pre- patent period as barber pole worm.

28. Egg laying capacity varies.

29. Eggs look the same as barber pole worm.“Scour” wormsImage source: NADIS UK

30. HELMINTHSTapeworms (cestodes)Over 1,000 species

31. Ribbon-like

32. Flat

33. Segmented

34. Hermaphrodites

35. Intermediate host

36. Visible in fecesUsuallyNon- pathogenic

37. Non disease-causing

38. No benefit to treatmentHELMINTHSFlukes (trematodes)Flat

39. Oval-shape

40. Leaf-like

41. Hermaphroditic