How quickly do anticoagulant rodenticides cause bleeding?

Clinical signs of coagulopathy typically appear 2–5 days after ingestion once factor II, VII, IX, and X are depleted. PT prolongation may be detected as early as 24–48 hours post-ingestion.

What is the antidote for anticoagulant rodenticide toxicity?

Vitamin K1 (phytonadione) is the specific antidote for anticoagulant rodenticide toxicity. Merck/MSD lists 2.5 mg/kg PO q12h for 28 days or 5 mg/kg PO q24h for 28 days, with confirmed warfarin exposure sometimes needing a shorter course. Recheck PT 2–3 days after stopping and extend treatment if PT remains prolonged.

Is there an antidote for bromethalin rodenticide toxicity?

There is no specific antidote for bromethalin. Treatment is supportive and includes decontamination, corticosteroids to reduce cerebral edema, mannitol for increased intracranial pressure, and supportive care. Prognosis is guarded with CNS signs.

Clinical decision support

Rodenticide toxicity calculator

Estimate rodenticide toxicity risk in dogs and cats with antidote and monitoring guidance.

Reference ranges & assumptions

Default LD50 values (mg/kg active ingredient)

Warfarin — Dog Warfarin — Cat

Bromadiolone — Dog Bromadiolone — Cat

Difenacoum — Dog Difenacoum — Cat

Brodifacoum — Dog Brodifacoum — Cat

Bromethalin — Dog Bromethalin — Cat

Cholecalciferol — monitoring threshold Cholecalciferol — high-risk threshold

Vitamin K1 dosing

Vitamin K1 q12h dose (mg/kg) Vitamin K1 q24h alternative (mg/kg)

LD50 values are estimates and vary by source. Bromethalin cats use the lower Merck/MSD sensitivity range. Cholecalciferol uses clinical monitoring thresholds because toxic changes occur far below LD50. Vitamin K1 should be given with a fatty meal for absorption.

Active ingredient dose

— mg/kg

Enter values

Enter weight, bait concentration, and amount to calculate.

Risk level —

—

Expected onset —

—

Specific antidote —

—

Monitoring plan —

—

Clinical next steps

Induce emesis if within 2 hours and patient is asymptomatic. Activated charcoal with cathartic for recent ingestions.
Anticoagulants: Vitamin K1 (phytonadione) is the antidote when indicated. Merck/MSD lists 2.5 mg/kg PO q12h or 5 mg/kg PO q24h for 28 days, with confirmed warfarin sometimes shorter. Recheck PT 2–3 days after stopping.
Bromethalin: No antidote. Decontamination is critical. Corticosteroids and mannitol for cerebral edema if CNS signs develop. Guarded prognosis with neurologic signs.
Cholecalciferol: Aggressive IV fluids (0.9% NaCl) to promote calciuresis. Monitor ionized calcium, phosphorus, BUN, creatinine. Furosemide and prednisone may help. Pamidronate for severe hypercalcemia.
For all exposures: baseline CBC, chemistry panel, and urinalysis. Monitor as indicated by toxicant type.

Safety checks

This tool supports calculation and education only.
It does not diagnose, prescribe, or replace current clinical references.
Verify patient-specific decisions with current toxicology references, hospital protocols, and veterinarian judgment.
Bait concentrations vary by product. Always verify the specific product label when possible.
Second-generation anticoagulants (bromadiolone, difenacoum, brodifacoum) have longer half-lives and require longer vitamin K1 therapy.

Basis and limits

Calculation basis: Active ingredient (mg) = bait amount (g) × concentration (% as decimal) × 1000. Or if ppm: mg = g × (ppm / 1,000,000) × 1000. Dose (mg/kg) = total mg / body weight (kg).
Assumed thresholds: anticoagulant and bromethalin defaults compare exposure to one-tenth of LD50, a conservative treatment-threshold estimate. Cholecalciferol uses lower clinical monitoring thresholds because toxic changes may occur far below LD50. Adjust assumptions to match specific references.
Anticoagulant monitoring: PT is the most sensitive coagulation test for anticoagulant rodenticide toxicity. Prolongation precedes clinical bleeding.
Scope: this tool estimates exposure. It does not replace toxicology consultation or clinical judgment.

Formula audit trail

1. Convert bait amount to grams if entered in ounces (oz × 28.35).

2. Convert concentration to % if entered in ppm (ppm ÷ 10,000).

3. Active ingredient (mg) = bait (g) × (% / 100) × 1000.

4. Dose (mg/kg) = active ingredient (mg) / body weight (kg).

5. Compare to the ingredient-specific treatment or monitoring threshold estimate from the assumptions panel.

Calculation steps will appear here for verification.

Related tools

Last reviewed: May 2026

Sources: ASPCA Animal Poison Control Center; Veterinary Partner; Merck Veterinary Manual

Rodenticide toxicity calculator

Next tools to check

Chocolate Toxicity Calculator

Xylitol Toxicity Calculator

NSAID Toxicity Calculator