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. Dose: 2.5–5 mg/kg PO q12h for 3–4 weeks for first-generation anticoagulants, and 4–6 weeks for second-generation anticoagulants (bromadiolone, difenacoum, brodifacoum).

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 — Dog Cholecalciferol — Cat

Vitamin K1 dosing

1st gen dose (mg/kg) 2nd gen dose (mg/kg)

LD50 values are estimates and vary by source. Adjust to match your toxicology reference. 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: Start vitamin K1 (phytonadione) PO with fatty meal. Check PT at 48–72h; if normal, continue for 3–4 weeks (1st gen) or 4–6 weeks (2nd gen). If PT prolonged, start vitamin K1 and monitor until normalized.
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 LD50s: defaults are commonly cited estimates. Triage compares exposure to one-tenth of LD50, a conservative treatment-threshold estimate. 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 species- and ingredient-specific one-tenth LD50 treatment-threshold estimate from 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

You might also find these helpful

Chocolate Toxicity Calculator

Xylitol Toxicity Calculator

NSAID Toxicity Calculator