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Parasite control in sheep
 

Parasite control in sheep

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This presentation on Internal Parasite Control in Sheep was given at the Indianhead Sheep Breeders Association 17th Annual Shepherd's Clinic and Trade Show on February 12, 2011.

This presentation on Internal Parasite Control in Sheep was given at the Indianhead Sheep Breeders Association 17th Annual Shepherd's Clinic and Trade Show on February 12, 2011.

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    Parasite control in sheep Parasite control in sheep Presentation Transcript

    • Internal parasite control in sheep
      SUSAN SCHOENIAN (Shāy-nē-ŭn)Sheep & Goat SpecialistWestern Maryland Research & Education Centersschoen@umd.edu - www.sheepandgoat.com
    • Internal parasites: the realities
      Internal 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
    • What is a parasite?
      A (generally undesirable) living organism that exists by stealing the resources produced or collected by another living organismSource: Wiktionary
    • 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.
    • 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)
      Coccidia
      Giardia
      Cryptospordium
    • HELMINTHS
      Nematodes (roundworms)
      • Over 20,000 species
      • Long
      • Round
      • Not segmented
      • Microscopic
      • Sexual reproduction
      • Male and female worms
      • Haemonchus contortus Barber pole worm
      Scour worms
      • Trichostrongylus spp. Hair worm
      • Teladorsagia
      Brown stomach worm
      • Oesophagostomum
      Nodule worm
      • Nematodirus spp.
      Threadworm
      Other
      • Lungworms
      • Meningeal worm
    • NEMATODE
      • Blood sucker
      • Found in abomasum
      • Most pathogenic
      • Causes anemia, bottle jaw, and death.
      • Prolific egg producer
      • Direct life cycle
      • Requires warmth (60°F) and moisture to complete its life cycle
      • Short 3 week life cycle
      Barber pole wormHaemonchus contortus
    • NEMATODES
      • Found in abomasum and Intestines.
      • Usually found in mixed infections with barber pole worm.
      • Not as pathogenic as barber pole worm.
      • Cause digestive problems (scouring) and ill thrift.
      • Similar life cycle and pre- patent period as barber pole worm.
      • Egg laying capacity varies.
      • Eggs look the same as barber pole worm.
      “Scour” worms
      Image source: NADIS UK
    • HELMINTHS
      Tapeworms (cestodes)
      • Over 1,000 species
      • Ribbon-like
      • Flat
      • Segmented
      • Hermaphrodites
      • Intermediate host
      • Visible in feces
      Usually
      • Non- pathogenic
      • Non disease-causing
      • No benefit to treatment
    • HELMINTHS
      Flukes (trematodes)
      • Flat
      • Oval-shape
      • Leaf-like
      • Hermaphroditic
      • Require intermediate host: snail, slug
      • Damage liver
      • Cause anemia
    • PROTOZOA
      Coccidia
      • Single-cell
      • Spore-forming
      • Microscopic
      • Can reproduce sexually or asexually
      • Species-specific
      • Eimeria spp.
      • Cause scouring
      • Damage lining of small intestines.
      • Treat with amprolium (Corid) or sulfa drugs.
      • Prevent with coccidiostats.
    • Integrated parasite management
      Parasites
      Life cycle
      Host resistance
      Management
      Clean or safe pastures
      Multi-species grazing
      Pasture rest and rotation
      Alternative forages
      Nutritional management
      Zero grazing
      Genetic selection
      Manage refugia
      Targeted selective treatment
      Your approach to internal parasite control should be integrated or holistic.
    • Parasite identificationWhat kind(s) of parasites are affecting your sheep?
      Fecal egg flotation
      • To differentiate between strongyle (stomach) and tapeworm eggs and coccidia oocytes.
      • Can’t differentiate between strongyle (stomach) worm eggs except Nematodirus)
      Do-it-yourself
      Public lab
      Diagnostic lab
      Private lab
      Veterinarian
      Larval id
      To differentiate between strongyle (stomach) worms (H. contortus, Teladorsagia, and trichostrongyles)
      University of Georgia
      Other universities
      Lectin-staining test
      Determine percent of Haemonchus contortus eggs in a fecal sample
      Oregon State University
      University of Georgia
    • Life cycle
      • Eggs hatch and develop into infective larvae (L3).
      • Sheep ingest infective 3rd stage larvae (L3).
      • Immature adults (L4) and adult worms suck blood.
      • Adult worms lay eggs.
    • Host resistanceSheep and lambs vary in their susceptiiblity to parasitism.
      More susceptible
      Weaned lambs
      Bummer lambs
      Late-born lambs
      Yearlings
      High-producing females
      Periparturient ewe
      Thin animals
      Geriatric sheep
      Unadapted breeds
      Stressed animals
      More resistant
      Mature sheep
      Dry ewes
      Pet sheep
      Mature wethers
      Sheep in good body condition
      Fat sheep
    • Management
      Good sanitation
      Use feeders
      Clean water
      Avoid overgrazing
      Do not graze below 2 inches.
      Time lambing to minimize parasite infections.
    • Pasture rest and rotation
      Pasture rotation is a recommended strategy for controlling internal parasites because it allows the use of cleaner (rested) pastures.
      Intensive rotational grazing may not help to reduce parasitism unless rest periods are long enough.
      Due to increased stocking rates, management intensive grazing may increase internal parasite problems in sheep and lambs.
      It takes about 2 months of rest for a contaminated pasture to become relatively “clean” for sheep grazing.
    • Use of clean or safe pastures
      A pasture that has not been grazed by sheep (or goats) for the past 6 to 12 months.
      A pasture that has been grazed by adult cattle and/or horses for the past 6 to 12 months.
      New pasture
      A pasture that has been renovated with tillage.
      A pasture in which a hay or silage crop has been removed.
      A pasture that has been rotated with row crops.
      A pasture that has been burned.
    • Alternative forages
      Livestock that browse have fewer parasite problems.
      Livestock grazing tall-growing forages will have less parasite problems.
      80% of parasite larvae is found in the first two inches of vegetative growth.
      Grazing tanniferous forages may reduce the effects of parasitism.
      Sericea lespedeza
      Chicory
      Birdsfoot trefoil
    • Multi-species grazing
      Sheep and goats share the same parasites, but they are different from the parasites that affect adult cattle and horses.
      Producers who graze multiple species of livestock report fewer parasite problems with small ruminants.
      Cattle and horses “vacuum” sheep/goat pastures of infective worm larvae.
      Sheep, goats, and cattle have complementary grazing habits.
    • Nutritional management
      Animals on a high plane of nutrition and in better body condition are better able to withstand worm burdens.
      Nutrition in early pregnancy (fat stores) can affect the immune response to internal parasites.
      Sheep receiving higher levels of protein prior to lambing have lower fecal egg counts.
      Supplementing grazing lambs with protein has been shown to reduce fecal egg counts.
      Nutritional supplementation is most likely to be beneficial when pregnant females and young animals are below optimal body condition at a time when pasture quality and/or quantity is limited.
    • Zero grazing
      Sheep raised in confinement or dry lot (zero grazing) tend to have fewer worm problems.
      Sheep put in confinement or dry lot do not usually get re-infected with worms.
      Coccidiosis could still be a problem, if preventative measures are not taken.
      Good sanitation
      Proper feeders
      Coccidiostats
    • Genetic selection
      Breeds vary in their resistance to gastro-intestinal parasites.
      Resistant breeds: Gulf Coast Native, Katahdin, St. Croix, Barbado.
      There is as much difference within breeds as between breeds.
      The 80-20 ruleApproximately 20 percent of the flock sheds 80 percent of the eggs onto pasture.
      Parasite traits are moderately heritable.
      Selection for parasite resistance will not adversely affect the growth of lambs or fertility of ewes.
      Resistance
      Ability of host to resist infection
      Measured by fecal egg counts
      Resilience
      Ability of host to withstand challenge and/or infection.
      For barber pole worm: measured by packed cell volume.
    • Slow down drug resistanceRufugia are worms that have not been exposed to anthelmintic treatment.
      Do not deworm on a regular schedule.
      Do not deworm all animals in a group.
      Do not return treated animals to a clean pasture.
      Give all anthelmintics orally at the proper dose.
      Do not underdose.
      Deworm new animals with anthelmintics from two different chemical classes.
      Without refugia, worms will eventually be resistant to all anthelmintics.
    • Targeted selective treatmentFive Point check©
    • FAMACHA© eye anemia score
    • Body condition score (BCS)
    • Dag Scores
    • Bottle jawSub-mandibular edema
    • Nasal discharge
    • Fecal egg countseggs per gram of feces
      Indicate “potential” parasite burden in animal.
      Indicate potential parasite contamination.
      Use to determine level of drug efficacy.
      Use to determine genetic differences in parasite resistance.
    • Limitations of fecal egg counts
      Fecal egg counts are not always well-correlated with disease.
      Presence of eggs or does not mean that the animal is clinically parasitized and needs treatment.
      Absence of eggs or oocytes (coccidia) does not mean that the animal is parasite-free and not needing treatment.
    • Fecal egg count interpretatoin
    • Three classes of anthelmintics
      Benzimidizoles
      Nicotinic agonists
      Macrocylic lactones
    • Benzimidazoles (BZD)
      characteristics
      White dewormers
      Water soluble
      Broad spectrum
      Wide margin of safety
      Efficacy against tapeworms
      Efficacy against liver flukes (albendazole)
      Widespread resistance
      Resistance is caused by dominant gene
      products
      Fenbendazole [Rx]SafeGuard®, Panacur®
      AlbendazoleValbazen®
      Oxyfendazole [Rx]Synanthic®
    • Nicotinic agonists
      characteristics
      Levamisole
      Clear drench
      Water soluble
      Broad spectrum of activity
      Not effective against arrested larvae
      Narrower margin of safety
      Resistance reported
      Resistance is caused by a recessive gene
      Morantel and Pyrantel
      Not effective against larval stages
      products
        Imidazothiaoles (IMID)
      LevamisoleProhibit®, Levasol®
       Tetrahydropyrimidines (TETR)
      Morantel [Rx]Rumatel®
      Pyrantel [Rx]Strongid®
    • Macrocylic lactones (ML)
      products
      Avermectins
      IvermectinIvomec®
      Doramectin [Rx]Dectomax®
      Milbemycins
      MoxidecinCydectin® Quest® [Rx]
      characteristics
      Broad spectrum
      Wide margin of safety
      Effective against external parasites
      Persistent activity
      Widespread resistance, reported especially ivermectin
      Resistance is caused by dominant gene
    • Improving (maintaining) the efficacy of treatment
      Weigh animals to determine proper dose.
      Do not underdose.
      Use proper drench technique.
      Fast animals prior to treatment.
      Give multiple anthelmintics [Rx]
      Synergetic effect
      Manage for refugia
    • How do you know if you have anthelmintic resistance on your farm?
      1) DrenchRite® Larval Development Assay
      2) Fecal Egg Count Reduction Test (FECRT)
      An in vitro test for the detection of resistance to all anthelmintic groups.
      Need pooled fecal sample from 10 or more animals (minimum of 6)
      at least > 350 epg >500 epg preferred
      Animals with FAMACHA© scores of 3, 4, or 5 are more likely to have higher egg counts if barber pole worm is the primary parasite.
      Comparison of before and after fecal egg counts
      Benzimidizoles7 days post-treatment
      Levamisole 7 days post-treatment
      Avermectins14 days post-treatment
      Should include “control” (untreated) animals in testing.
    • The future of parasite control
      “natural” anthelmintics
      Copper oxide wire particles
      Copper sulfate
      • Garlic
      • Pumpkin seed
      • Diatomaceous earth
      Pine bark
      Sericea lespedeza (leaf meal)
      Others
      Future
      Vaccine development
      They are testing a promising vaccine in Australia
      The European community has received a historically large grant to help develop vaccines for gastro-intestinal parasites in livestock.
      New anthelmintics
      Zolvix®Monepantel
      Startect®derquantel + abamectin
    • Small Ruminant Program
      Thank you for your attention.
      Any questions?
      Susan Schoeniansschoen@umd.eduwww.sheepandgoat.com