• Methiocarb is a carbamate pesticide used as an insecticide, acaricide, molluscicide and bird repellent.
• Mechanism of poisoning similar to organophosphate poisoning.
• Signs: hypersalivation, vomiting, tremor, dyspnea and convulsions.
• Diagnosis: history, clinical signs.
• Treatment: atropine to effect. Control nervous signs with diazepam.
  ⚠️Do not administer barbiturates or other cardiorespiratory depressants.
• Prognosis: excellent if treated early.

ℹ️Deliberate poisoning is common, with microgranules concealed in meat-based baits.

• Abdominal pain, hypersalivation, vomiting and diarrhea.
• Lacrimation.
• Dyspnea +/- coughing.
• Fine muscle tremors, ataxia.
• Clonic seizures.

• Hypersalivation.
• Urination and diarrhea.
• Sudden collapse.
• Respiratory distress.
• Death.

• Accidental poisoning is more common in rural areas.
• Methiocarb molluscicides were banned in the UK and EU in 2015.

• Exposure to methiocarb, a carbamate pesticide Carbamate poisoning.

• Carbamates are cholinesterase inhibitors → accumulation of acetylcholine → muscarinic and nicotinic effects of acetylcholine.
• Death, when it occurs, is due to respiratory failure.
• Methiocarb is rapidly absorbed by all routes, with rapid distribution.

Muscarinic effects

• Increase in all body secretions, including hypersalivation, lacrimation and an increase in pulmonary secretions.
• Vomiting and diarrhea.
• Abdominal pain due to increased peristaltic activity.
• Incontinence due to relaxation of the sphincters.
• Miosis, sometimes very prominent.
• Bronchial constriction.

Nicotinic effects

• Predominantly neuromuscular.
• Muscle fasciculations beginning at the head and neck, and progressing caudally.
• Muscle stiffness.
• Weakness progressing to paresis and paralysis.

• Clonic spasms.

CNS effects

• Initial anxiety and apprehension
• Depression.
• Convulsive episodes.

• Signs of poisoning occur within minutes to within six hours of exposure to the poison.
• The inhibition of cholinesterase by carbamates is reversible and does not last as long as with organophosphate insecticides Organophosphate insecticide poisoning.
• Death due to respiratory failure may occur within a few hours to several days.
• Occasionally → rapidly fatal asphyxia.

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.
• Corfield G S, Connor L M, Swindells K L et al (2008) Intussusception following methiocarb toxicity in three dogs. J Vet Emerg Crit Care 18 (1), 68-74 VetMedResource.
• Studdert VP (1985) Epidemiological features of snail and slug bait poisoning in dogs and cats. Aust Vet J 62, (8), 269-71 PubMed.
• Udall ND (1973) The toxicity of the molluscicides metaldehyde and methiocarb to dogs. Vet Rec 93 (15), 420-422 PubMed.

Other sources of information

• Talcott PA (2024) Organophosphorus and Carbamate Anticholinesterase Pesticides. Blackwell’s Five-Minute Veterinary Consult Clinical Companion. Small Animal Toxicology. 3_rd edn. Wiley USA, pp 633-638.
• Dalefield R (2017) Veterinary Toxicology for Australia and New Zealand, pp 89-93.
• Peterson ME & Talcott PA (2006) Small Animal Toxicology, pp 941-955.
• Plumlee KH (2004) Clinical Veterinary Toxicology, 178-180.
• Lorgue G, Lechenet J & Reviere A (1966) Clinical Veterinary Toxicology, pp66-68.

• ASPCA Animal Poison Control Center. Website: www.aspca.org.
• Veterinary Poisons Information Service (VPIS). Website: www.vpisglobal.com.