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Carbamate poisoning
Synonym(s): Carbaryl, acetylcholinesterase inhibitor, methiocarb, toxicity, fungicide, herbicide
Introduction
- Cause: ingestion of insecticides, fungicides and herbicides derived from carbamic acid, thiocarbamic acid or dithiocarbamic acid, generally of low toxicity; mechanism of poisoning similar to organophosphate poisoning Organophosphorus poisoning.
- Signs: vomiting, tremor, convulsions.
- Diagnosis: history, clinical signs, response to atropine.
- Treatment: specific - atropine to effect; nervous signs - diazepam. The oximes, eg pralidoxime, are ineffective in carbamate poisoning. Do not administer barbiturates or other cardiorespiratory depressants.
- Prognosis: excellent if treatment administered early enough.
Presenting signs
Ocular signs- Lacrimation.
- Miosis.
- Initial apprehension.
- Ataxia.
- Lethargy.
- Muscle fasciculations.
- Jerky movements.
- Convulsions.
- Coma.
- Vomiting.
- Frequent diarrhea.
- Anorexia.
- Hypersalivation.
- Signs of abdominal discomfort eg pressing ventral abdomen on cold concrete.
- Dyspnea.
- Coughing due to bronchial hypersecretion and bronchospasm.
- Epistaxis may occur.
Urinary signs
- Frequent urination.
Public health considerations
- Risk of contamination of humans from same source or during decontamination of dog.
Cost considerations
- Yes.
Pathogenesis
Etiology
- Carbamates, eg in fungicides and herbicides; in particular aldicarb, oxamyl, methiocarb, carbofuran, isolan, methomyl, formetanate, aminocarb, cloethocarb, bendiocarb, propoxur.
- Vary in toxicity, generally considered relatively safe (note above exceptions).
Pathophysiology
- Readily absorbed, fat soluble, diffuses readily into tissues.
- The most toxic carbamates, eg aldicarb (LD50 = 5-10 mg/kg), carbofuran (LD50 = 19 mg/kg).
- Block acetylcholinesterase (reversible) → accumulation of neurotransmitter acetylcholine → clinical signs; may → respiratory failure and death.
Timecourse
- Most cases mild with rapid onset over minutes - hours within ingestion or exposure.
- Death due to respiratory failure - a few hours to several days (depends on compound).
- Occasionally rapidly fatal due to asphyxia.
- Death may occur within a few hours to several days.
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.
- Tinson E, Boller E, Davis M (2017) A suspected case of intermediate syndrome in a dog with carbamate toxicosis. Aust Vet J 95 (6), 201-206 PubMed.
- de Siqueira A, Salvagni F A, Yoshida A S et al (2015) Poisoning of cats and dogs by the carbamate pesticides aldicarb and carbofuran. Res Vet Sci 102, 142-9.
- McEntee K, Poncelat L, Clerc X & Henroteaux M (1994) Acute polymyopathy after carbamate poisoning in a dog. Vet Rec 135 (4), 88-90 PubMed.
- Fikes J D (1990) Toxicology of selected pesticides, drugs and chemicals - organophosphorus and carbamate insecticides. Vet Clin NA 20 (2), 353-367 PubMed.
Other sources of information
- Lorgue G, Lechenet J & Reviere A (1966) Clinical Veterinary Toxicology. pp 66-68.
- Dalefield R (2017) Veterinary Toxicology for Australia and New Zealand. Elsevier, USA. pp 89-93.
- Peterson M E and Talcott P A (2007) Small Animal Toxicology. 2nd edn. Elsevier, USA. pp 941-955.
- Plumlee K H (2004) Clinical Veterinary Toxicology. Mosby, USA. pp178-180.
Organisation(s)
- American Society for the Prevention of Cruelty to Animals (ASPCA), Animal Poison Control Center. Website: www.aspca.org. Tel: +1 (888) 426 4435.
- Veterinary Poisons Information Service (VPIS. Website: www.vpisglobal.com., Tel: + 44 (0)2073 055 055.