VPT 421: Veterinary Toxicology (2+0)

CLINICAL SYMPTOMS

• Three categories of effects occur in poisoned animals: muscarinic, nicotinic, and central nervous system effects.

  • Muscarinic effects include profuse salivation, lacrimation, serous or seromucous nasal discharge, increased respiratory sounds due to bronchoconstriction and excess bronchial secretions, pronounced gastrointestinal sounds, colic and diarrhoea due to increased gastrointestinal motility, bradycardia, pupil constriction, sweating, coughing, vomiting and frequent urination. These parasympathetic signs usually begin appearing first.
  • Signs of nicotinic cholinergic overstimulation occur soon after the onset of muscarinic signs and include muscle fasciculation, tremors, twitching, spasm and hypertonicity causing a stiff gait or rigid stance.
  • Central nervous system effects vary with species and severe CNS depression common in any species. Anxiety, restlessness and hyperactivity may also be noticed.
  • Death is usually due to respiratory failure, but, bronchoconstriction and convulsions may be life threatening.

• Chronic organophosphorus poisoning

• The symptoms of chronic poisoning include polyneuritis, demyelination, sensory disturbances, muscle weakness, tenderness, depressed tendon reflexes, lower and upper motor neuron paralysis. The mechanism of action is not very clear. But, it is not due to anticholinesterase activity. No specific treatment is available.