Parasite Control In Youngstock

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Parasite Control In Youngstock

• John G Cook BVSc DCHP MRCVS

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Worm Species

• Gut worms (Ostertegia ostertagi, Nematodirus
  helvetianus, Cooperia oncophora)
• Lungworms (Dictyocaulus viviparous)
• Liver Fluke (Fasciola hepatica)

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Clinical Disease

• Imbalance between development of immunity and
  weight of infection.
• Availability of large numbers of the infective
  stages of the parasite.
• Presence of susceptible cattle on the
  contaminated grazing area.

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Old diseases

• Lungworm controllable by vaccination (Huskvac).
• Gut worms controllable by grazing management and
  anthelmintic use.
• Does not need expensive drugs.

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Types of disease

• Type I Ostertagiasis-watery diarrhoea,young
  calves at grass, early season. Adult worms in gut
• Type II Ostertagiasis-yearlings late winter/early
  spring. Arrested development in abomasal wall.
• Strain dependant brought about by cold stress
  dessication on pasture

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Methods of Control

• Lungworm-vaccination. Disease usually seen late
  summer September onwards.
• Gutworms-Evasive strategies, Weybridge or dose
  and move system
• Suppressive strategies-repeat/sustained
  treatments with anthelmintics
• Avoidance strategies-clean grazing
• Dilution stategies.

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Development of Drug Resistance

• Genetic, irreversible change, a real threat.
• Dependant upon balance between worm population in
  host and that in refugia-i.e.not exposed to
  anthelmintics.