ISSN 2398-2993      

Rodenticide poisoning

obovis
Contributor(s):

Nicola Bates

Paul Wood

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Synonym(s): Rodenticide toxicity, Rat poisoning, Anticoagulant toxicity


Introduction

  • Cause: ingestion of anticoagulant rodenticide.
  • Signs: weakness, anemia and hemorrhage.
  • Diagnosis: history of exposure and signs suggestive of anemia and hemorrhage.
  • Treatment: vitamin K1 therapy.
  • Prognosis: depends on the extent and location of hemorrhage. 

Pathogenesis

Etiology

  • Rodenticides are widely used on farmland and may be stored in large quantities.
  • Grain may be dressed with anticoagulant rodenticide to reduce damage and loss through rodent infestation. It will be readily eaten by cattle if they gain access.
  • Large acute ingestion and low level chronic exposure may cause toxic effects.

Predisposing factors

General

  • These compounds have long half-lives and animals with recent exposure will be at increased risk of bleeding if re-exposed.

Specific

  • Animals with liver disease may be more at risk because of inability to synthesize clotting factors and decreased metabolism of the rodenticide.

Pathophysiology

  • Vitamin K is a cofactor in the activation of clotting factors II (prothrombin), VII, IX and X. Without vitamin K these coagulation proteins remain in a non-functional state.
  • Anticoagulants act by inhibiting hepatic vitamin K1 epoxide-reductase, the enzyme responsible for conversion of vitamin K1 epoxide to vitamin K1.
  • There is gradual depletion of the body stores of vitamin K1 needed to convert precursor coagulation proteins to their activated forms.
  • There is a reduction in Factors II (prothrombin), VII, IX and X and therefore inhibition of prothrombin synthesis within the liver.
  • Once vitamin K1 and the clotting factors have been depleted bleeding occurs. Hence the lag-time before onset of signs.

Timecourse

  • Variable; several days after acute large ingestion, and longer after low dose chronic exposure.

Epidemiology

  • Rarely reported in cattle, but may be underdiagnosed.

Diagnosis

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Treatment

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Prevention

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Further Reading

Publications

Refereed Papers

  • Recent references from PubMed and VetMedResource.
  • Berny P, Alves L, Simon V, Rossi S (2005) Anticoagulant rodenticide poisoning in ruminants: evidence from field cases. Revue de Médecine Vétérinaire 156 (8-9), 449-454.
  • Brito M F, Seixas J N, Jabour F F, Andrade G B et al (2005) About an outbreak of coumarin poisoning in cattle. Pesquisa Veterinária Brasileira 25 (3), 143-149.
  • Haskell S R, Payne M, Webb A, Riviere J, Craigmill A L (2005) Antidotes in food animal practice. JAVMA 226 (6), 884-7 PubMed.
  • Hornfeldt C S, Phearman S (1996) Successful treatment of brodifacoum poisoning in a pregnant bitch. JAVMA 209 (10), 1690-1691 PubMed.
  • O’Scannail T (1991) Suspected warfarin poisoning in a calf. Ir Vet J 44 (40).
  • Fox F H, Rebhun W C (1983) Warfarin poisoning with complications in a heifer. Vet Med Small Anim Clin 78 (10), 1611-1613.
  • Pugh D M (1968) The abortifacient action of warfarin cattle. Br J Pharmacol 33, 210.
  • Papworth D S (1958) A review of the dangers of warfarin poisoning to animals other than rodents. Journal of the Royal Society of Health 78 (1), 52-60 PubMed.

Other sources of information

  • Briggs G C, Freeman F K, Towers C V, Forinash A B (2017) Drugs in pregnancy and lactation. 11th edn. Ed: Wolters Kluwer. USA. pp 1169-1170.

Organisation(s)

  • ASPCA Animal Poison Control Center (2017) [online] Last accessed 27th November 2017. Available at: www.aspca.org.
  • Veterinary Poisons Information Service (2017) [online] Last accessed 27th November 2017. Available at: www.vpisglobal.com

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