Parasite control in dairy sheep


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Presentation for 18th Annual Symposium of Dairy Sheep Producers of North America. October 2012.

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Parasite control in dairy sheep

  2. 2.  Primary health problem affecting sheep and lambs, especially east of the Rockies. Severity varies by • Geographic region • Production system Control is limited by effectiveness of anti- parasitic drugs (called anthelmintics).
  3. 3.  Eliminate parasites1. Prevent clinical disease, production losses, and mortality, and …2. Slow down drug resistance.
  5. 5.  Parasite biology Integrated parasite management (IPM) 1. Pasture management 2. Animal factors/ management 3. Deworming Anthelmintics Anthelmintic resistance
  6. 6. 1. Multi-cellular (Helminths) a) Nematodes (roundworms) b) Cestodes (tapeworms) c) Trematodes (flukes)2. Single-cell (protozoa)
  7. 7. 1. Strongyle2. Lungworms3. Meningeal worm
  8. 8.  Haemonchus contortus Teladorsagia (Ostertagia) Trichostrongylus Nematodirus Oesophagostomum Cooperia Trichuris ovis Bunostomum
  9. 9.  Short, direct life cycles that are weather-dependent. L4, adult Can overwinter on pasture. Ability to go into hypobiotic (arrested) state (in host) when environmental conditions are not L3 conducive to their development. Vary in their egg laying ability. L1 L2 Eggs look same under microscope.
  10. 10.  Primary parasite affecting sheep and lambs in warm, moist climates and/or with summer-dominated rainfall. Most pathogenic species Blood-sucker Image from University of Georgia Prolific egg layer
  11. 11. SYMPTOMS(due to blood and protein loss) Anemia (paleness) Edema - “bottle jaw” (accumulation of fluid) Not usually diarrhea Weight loss Loss of body condition Poor stamina Sudden death
  12. 12. SYMPTOMS(usually additive w/barber pole worm) Production loss Weight loss Dagginess Scours (diarrhea) Only occasional death Image source: NADIS UK
  13. 13.  Usually not significant Usually additive in effect Possible respiratory symptoms  Coughing  Irritated airways  Pneumonia Difficult to diagnose  Usually no clinical signs  Larvae (not eggs) in feces  Post-mortem diagnosis
  14. 14.  Normal parasite of white tail deer. Sheep are an abnormal host.  Ingest intermediate host (snail or slug)  Larvae migrates into central nervous system where it causes neurological disease (various symptoms). Treat with repeated doses of fenbendazole and anti- inflammatory drugs. Monthly treatments with ivermectin have been used as a preventative (camelids). Paralaphostrongylus tenius
  15. 15.  Indirect life cycle; require pasture mite as an intermediate host. Tend to be non- pathogenic Usually no benefit to treatment. Treat with albendazole (Valbazen®), fenben- dazole (Safeguard®, or praziquantel (Quest Plus®). Moniezia expansa
  16. 16.  Regional problem Fasciola hepatica (Gulf States, Pacific Northwest) Require an intermediate host (snail or slug) Infect bile ducts - liver damage Diagnosis based on finding eggs in feces and post-mortem Similar symptoms as barber pole worm (anemia and bottle jaw) Treat with albendazole (Valbazen®) or clorsulon (Ivomec® Plus).
  17. 17.  Species-specific  10 species known to infect sheep, but not all are pathogenic. More complicated life cycle than most roundworms. Cause damage to cells lining small intestines. Most prevalent  Indoor pens  Feed lots Eimeria spp.  Intensive grazing areas
  18. 18. FECAL EXAM CLINICAL SIGNS Of limited value –  Adults are largely shouldn’t use as sole immune, but serve as a diagnostic tool reservoir of infection.  Lambs (1-6 mos., esp. 4-8  Can have clinical coccidiosis with low oocyte count and wks.) are very susceptible. vice versa.  Scours (diarrhea)  Not all species of coccidia  Open fleece are pathogenic.  Weight loss  Is normal to find coccidia  Anorexia oocytes in fecal samples.  Dehydration  Weakness
  19. 19.  Good sanitation Coccidiostats in feed, mineral, water, and/or milk replacer.  Lasalocid (Bovatec®)  Monensin (Rumensin®)  Decoquinate (Deccox®)  Amprolium (Corid)
  20. 20.  Medicate water or drench individual animals (preferable).  Anthelmintics 1. Amprolium (Corid) 2. Sulfa antibiotics ▪ Di-Methox® ▪ Sulmet® All Tx’s require veterinary Rx. Supportive therapies
  21. 21.  A method of controlling parasites using a combination of chemical and non- chemical means.1. Non-chemical ▪ Pasture management ▪ Animal management2. Chemical ▪ Proper and judicious use of drugs
  22. 22. 1) Safe pastures2) Low risk pastures3) Evasive grazing4) Strip grazing5) Rotational grazing6) Multi-species grazing
  23. 23. Chicory7) Compost manure before spreading8) Alternative forages9) Minimum grazing height10) Delay grazing11) Night penning12) Zero grazing Sericea lespedeza
  24. 24. 1) Host immunity2) Lambing management3) Nutrition4) Genetics
  25. 25. 1. FAMACHA© System2. Five Point Check© Fecal egg counting
  26. 26.  A system developed in South Africa to assess barber pole worm infection and determine the need for deworming. Scores estimate packed cell volume (PVC) by measuring anemia using Eye lid color PCV Treatment recommendation a color eye chart. 1 Red > 28 Optimal No 2 Red-Pink 23-27 Acceptable No Each score has a 3 Pink 18-22 Borderline ? treatment 4 Pink-White 13-17 Dangerous Yes recommendation. 5 White < 12 Fatal Yes
  27. 27.  An extension of the FAMACHA© system that includes evaluation criteria for other important internal (and external) parasites. Includes five check points on the animal: 1. Ocular membrane (eye) 2. Bottle jaw 3. Body condition score 4. Dag score (scours) 5. Nasal discharge (nose bots)
  28. 28.  Determining the number of worm eggs per gram of feces (EPG) in order to estimate the worm burden in an animal. Egg count includes all strongyle eggs; cannot differentiate at egg stage. Requires a measured amount of feces and flotation solution. A McMaster slide is used to count eggs. Most veterinarians and many diagnostic labs do not perform quantitative egg counts (only simple fecal flotations).
  29. 29.  Individual sample to determine need for deworming individual animal. Individual or pooled samples to determine level of pasture contamination. Pooled sample to determine treatment need in a large flock, where FAMACHA© and Five Point Check® are not practical. Individual samples to determine effectiveness of anthelmintic treatment (FECRT) or management strategy. Individual samples to determine genetic differences in parasite resistance.
  30. 30. MACROCYLICBENZIMIDAZOLES LACTONES NICOTINICS1. Fenbendazole 1. Avermectins 1. Levamisole SafeGuard® Ivermectin (Prohibit®) Panacur® (Ivomec®) Eprinomectin 2. Pyrantel2. Albendazole (Eprinex®) (Strongid®) Valbazen® Doramectin (Dectomax®) 3. Morantel3. Oxybendazole (Rumatel®) Synanthic® 2. Milbimycins Moxidectin (Cydectin®)
  31. 31. SHEEP AND LAMBS LACTATING DAIRY EWES Ivermectin  Withdrawal periods have (Ivomec® drench) not been established for lactating dairy ewes. Albendazole  Requires extra-label drug (Valbazen® liquid) use, as prescribed by a First 30-d gestation licensed veterinarian. Moxidectin  Work with veterinarian to (Cydectin® drench) establish safe withdrawal periods for milk. Levamisole (Prohibit® drench)
  32. 32. ORAL DRENCHES INJECTABLES POUR-ONS FDA-approved  Not FDA-  Not-FDA for sheep. approved. approved. Easier to  Sub-  Not developed administer. therapeutic for sheep skin. Clear system levels select for  Less effective. faster. resistant  Sub- Shorter worms. therapeutic withdrawal  Longer levels select for periods. withdrawal resistant More effective periods. worms.
  33. 33. 1) When an anthelmintic treatment fails to reduce fecal egg counts by 95% or more; severe when less than 60%.2) There is varying degrees of resistance to all anthelmintic classes.  Benzimidazoles - widespread  Avermectins - widespread  Moxidectin - emerging  Levamisole - variable3) Resistance varies by geographic location and farm and is influenced by past anthelmintic use.
  34. 34.  Each anthelmintic family has a different way to kill worms. Worms develop resistance to the mechanism of worm control not individual drugs. There is cross resistance among drugs in the same family. If a different drug in the same family appears to work, its efficacy will be short-lived.
  35. 35. 1) Treatment response2) Fecal egg count reduction test (FECRT) ▪ Before (d-0) and after fecal egg counts (d 10-14)3) DrenchRite® test Larval development assay (LDA)
  36. 36.  Decrease frequency of treatments. Do not treat everyone; leave some animals untreated. Do not move treated animals to a clean pasture. Do not deworm when there is a low level of pasture contamination. Re-introduce suceptable worms.
  37. 37.  By exposing worms to sub-therapeutic levels of drugs. 1) Underdosing 2) Using injectable dewormers 3) Using pour-on dewormers 4) Depositing drug into mouth instead of esophagus. 5) Persistent activity dewormers (?)
  38. 38. For sale To prevent the Ram - $1,000 Resistant worms - free introduction of resistant worms to your farm, deworm all newly acquired animals with anthelmintics from all three chemical classes.
  39. 39. NATURAL “ANTHELMINTICS” NEW ANTHELMINTICS Copper oxide wire particles  Monepantel (Zolvix®) Copper sulfate  Derquantel + abamectin Nicotine sulfate (Startect®) Diatomaceous earth Pumpkin seed Garlic  Nematode trapping fungus Papaya Sericea lespedeza FUTURE (?) (leaf meal)  Vaccine for Haemonchus? Pine bark contortus (in development)? Others
  40. 40.  American Consortium for Small Ruminant Parasite Control Maryland Small Ruminant Page Sheep 201: A Beginner’s Guide to Raising Sheep Today’s PowerPoint presentation
  41. 41. Thank ewe for your attention. Lambs are 69% Katahdin x 31% Lacaune.