Rat poison toxicity in pets

Bromethalin is a neurotoxic rodenticide that is not an anticoagulant, and vitamin K1 is not an antidote. It works by uncoupling oxidative phosphorylation, which decreases ATP production and impairs the function of the sodium-potassium pump. This leads to cerebral edema and increased cerebrospinal fluid (CSF) pressure. Lipid peroxidation also contributes to its toxic effects. Symptoms of bromethalin poisoning can appear within hours to days and may include tremors, seizures, and paralysis.

• Neurological: CNS depression, ataxia, muscle tremors, seizures, paresis/paralysis, hyperthermia, and coma.

• Ocular: Abnormal pupillary light reflex (PLR), anisocoria (unequal pupils), and nystagmus.

• Gastrointestinal: Anorexia, nausea, and vomiting (uncommon).

• Respiratory: Respiratory depression, which may be fatal.

Exposure Severity:

• Supra-lethal Doses (≥LD50): Acute CNS excitation, muscle tremors, and seizures.

• Sub-lethal Doses (<LD50): Symptoms may be delayed 2–7 days, with some delays up to 2 weeks. Common signs include anorexia, progressive ataxia, paresis, hindlimb paralysis, muscle tremors, focal or generalized seizures, and abnormal eye movements.

• Severe Cases: Forelimb extensor rigidity and decerebrate postures are often observed.

Recovery:

• Mild Poisoning: Clinical signs may resolve within 1–2 weeks, though in some cases, symptoms may persist for 4–6 weeks.

• Gastrointestinal Decontamination:

  • Induce emesis in asymptomatic animals if ingestion was recent.

  • Administer activated charcoal (0.5–1 mg/kg PO every 4–8 hours for 2–3 days) to reduce absorption.

  • An osmotic cathartic (sodium sulfate, 125 mg/kg PO) is given with the first dose of activated charcoal.

• Intravenous Lipid Emulsions (ILE):

  • In severe cases, a 20% ILE bolus (1.5 mL/kg over 2–3 minutes) or a continuous infusion (0.25 mL/kg/min for 30–60 minutes) may be used.

  • Discontinue if no clinical improvement after three doses. Be aware of possible adverse effects related to contamination or reactions to the emulsion.

Hospital Care:

• Severe CNS and Respiratory Depression: Hospitalization is often required, with mechanical ventilation if respiratory function is compromised.

• Nursing Care: Maintain normal body temperature, provide padded bedding, and rotate the patient every 6 hours to prevent atelectasis.

Drugs for Supportive Care:

• Cerebral Edema Control: Mannitol (250 mg/kg every 6 hours IV), dexamethasone (2 mg/kg every 6 hours IV), and furosemide (1–2 mg/kg every 6 hours IV) may help but have limited efficacy.

• Seizure and Muscle Tremor Control: Diazepam (1–2 mg/kg IV), midazolam (0.2–0.4 mg/kg IV), or phenobarbital (5–15 mg/kg IV) can be used as needed.

Antidote:

• There are no known effective antidotes for bromethalin poisoning.

Immediate veterinary intervention is critical for bromethalin poisoning. Mild cases may resolve with close monitoring and supportive care within 3–7 days. However, the prognosis is guarded to poor in cases involving severe CNS or respiratory depression, coma, or paralysis.