Poisons, toxins and tapeworm

• Classification of poisons and toxins

  • Based on origin = natural or artificial
• Acute effect

  < 1 week
• Chronic exposure

  > 3 months
• Factors affecting susceptibility to poisons/toxins

  • Species difference
  • Breed difference
  • Previous history
  • Physiological state
• Poisonous Plants - A1 Alkaloids

  Alkaline like

  largest group - 4,000 different compounds

  modified in liver prior to excretion

  many have therapeutic uses
• Plants - A2 Glycosides

  Non-toxic

  positive effects on health
• Types of A2 Glycosides

  • Cyanogenic
  • Goitrogenic
  • Cardiac
  • Saponins
• Plants - A3 Nitrates + nitrites

  Plants take up N as nitrate from soil

  converted to toxic nitrites when eaten

  forms methaemoglobin
• Plants - A4 Oxalates

  Found in most plants with variable amounts

  seasonal variation

  influenced by soil type
• Pesticides

  Human made toxins

  different chemicals

  can affect non - target animals
• Minerals

  Toxic in excess

  lead to chronic toxicity
• Mycotoxins

  Over 500, produced by moulds
• Types of parasites

  • Endo-parasite (live inside)
  • Ecto-parasite (live outside)
• Diagnosis of horse tapeworm is difficult because egg detection in horse faeces is not reliable by standard methods and not finding eggs in faeces does not mean tapeworms are absent
• Features of horse tapeworm

  • 8 - 25 cm long
  • Head (scolex) has four suckers that attach to organs
  • Flattened tail (strobila)