ISSN 2398-2993      

Metaldehyde toxicity

obovis
Contributor(s):

Nicola Bates

Alan Murphy

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Synonym(s): slug and snail bait, molluscicide


Introduction

  • Cause: ingestion of metaldehyde, usually as slug bait.
  • Signs: ataxia, twitching and convulsions.
  • Diagnosis: based on history and clinical signs.
  • Treatment: supportive.
  • Prognosis: poor in animals with significant neurological signs.

Pathogenesis

Etiology

  • Metaldehyde is a common ingredient of molluscicide preparations.
  • It is typically available as small blue/green coloured pellets containing 1.5 to 6% w/w metaldehyde in a bran/wheat filler.
    • Also sold in liquid, dust and granular forms.
    • It may be combined with molasses, enhancing its palatability.
  • There is limited information on toxic doses in cattle:
    • A dose of 0.2 g/kg has been fatal in adult cattle.
    • Even a small quantity can be fatal in calves:
      • Death within 2 hours occurred in a calf that licked an empty container that had previously held metaldehyde slug pellets.
    • Trial work indicates a lethal dose of 100-600 mg/kg but all work has been conducted in non-ruminant mammals.

Pathophysiology

  • The mechanism of metaldehyde toxicity is not clearly understood.
  • It is not clear if metaldehyde itself is the cause of the effects seen or acetaldehyde, a product of metaldehyde hydrolysis by acid.
  • Toxic effects may involve changes in neurotransmitter concentrations which has been demonstrated in metaldehyde-poisoned experimental animals.
  • Further information can be found via Linda K Dolder: Toxicology Brief – see references section below.

Timecourse

  • Onset can be very rapid:
    • Can occur within 1-3 hours of ingestion.
    • Often within 30 minutes.
    • In ruminants, particularly if a relatively low dose has been ingested, effects may occur within 12-24 hours due to retention in the rumen.
    • In severe cases death can occur within a few hours or 24-48 hours after onset of signs.

Epidemiology

  • Poisoning can occur wherever metaldehyde is used.
  • Most cases in cattle occur when they gain access to storage areas.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • SAC C VS Disease Surveillance Report (2011) Cases of poisoning in Scottish cattle and sheep. Vet Rec 169, 628-631 PubMed.
  • Daniel R, Lewis D, Payne J (2009) Metaldehyde poisoning in a dairy herd. Vet Rec 165(19),57-58 PubMed.
  • Valentine B A, Rumbeiha W K, Hensley T S, Halse R R (2007) Arsenic and metaldehyde toxicosis in a beef herd. J Vet Diagn Invest 19, 212-215 PubMed.
  • Booze T F, Oehme F W (1985) Metaldehyde toxicity: a review. Vet Hum Toxicol 27 (1),11-19.
  • Homeida A M, Cooke R G (1982a) Pharmacological aspects of metaldehyde poisoning in mice. J Vet Pharmacol Ther 5,77-81.
  • Homeida A M, Cooke R G (1982b) Anti-convulsant activity of diazepam and clonidine on metaldehyde-induced seizures in mice: effects on brain gammaamino butyric acid concentrations and monoamine oxidase activity. Vet Pharmacol Ther 5,187-190.
  • Longbottom G M, Gordon A S (1979) Metaldehyde poisoning in a dairy herd. Vet Rec 104(20), 454-455.
  • Stubbings D P, Edgington A B, Lyon D G, Spence J B, Clark M H (1976) Three cases of metaldehyde poisoning in cattle. Vet Rec 98(18), 356-357.
  • Williams B M, Thomas A I (1976) Metaldehyde poisoning in cattle. Vet Rec 98(18), 358-359.
  • Egyed M N, Brisk Y L (1966) Metaldehyde poisoning in farm animals. Vet Rec 78, 753-754.

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