Is Warfarin safe for dogs and cats?
Elevated risk for petsWarfarin and related anticoagulant rodenticides are among the most common causes of fatal canine poisoning; while therapeutic warfarin is rarely used in veterinary medicine today, accidental ingestion of warfarin-based rodenticides (and especially second-generation superwarfarins — brodifacoum, bromadiolone, diphacinone) is a major veterinary emergency. First-generation rodenticides: warfarin (0.005–0.025% in baits); designed to require repeated ingestion for lethality; a single ingestion of a standard bait station by a dog typically does not cause anticoagulant coagulopathy — but dose-dependent risk exists. Second-generation superwarfarins: brodifacoum, bromadiolone, diphacinone in 'all-weather' blocks are far more potent and have much longer durations of action (weeks to months) than warfarin; single-bait-block ingestion can cause severe coagulopathy in dogs lasting 3–6 weeks; treatment requires prolonged vitamin K1 therapy. Relay toxicosis: dogs can be secondarily poisoned by eating rodents that died from superwarfarins — particularly important in hunting dogs and scavenging breeds. Clinical signs: delayed 2–5 days after ingestion; lethargy, dyspnea (hemothorax), pale mucous membranes, epistaxis, hematomas, hematuria, hemarthrosis; PT and APTT markedly prolonged. Treatment: vitamin K1 (phytonadione) 2.5–5 mg/kg/day orally for warfarin (2–4 weeks) or superwarfarins (4–6 weeks); whole blood or plasma transfusion for active hemorrhage; hospitalization for severe cases.
What is warfarin?
The IUPAC name is 4-hydroxy-3-(3-oxo-1-phenylbutyl)chromen-2-one.
Also known as: 4-hydroxy-3-(3-oxo-1-phenylbutyl)chromen-2-one, Coumafene, Zoocoumarin, Coumafen.
- IUPAC name
- 4-hydroxy-3-(3-oxo-1-phenylbutyl)chromen-2-one
- CAS number
- 81-81-2
- Molecular formula
- C19H16O4
- Molecular weight
- 308.3 g/mol
- SMILES
- CC(=O)CC(C1=CC=CC=C1)C2=C(C3=CC=CC=C3OC2=O)O
- PubChem CID
- 54678486
Risk for dogs
Elevated riskWarfarin and related anticoagulant rodenticides are among the most common causes of fatal canine poisoning; while therapeutic warfarin is rarely used in veterinary medicine today, accidental ingestion of warfarin-based rodenticides (and especially second-generation superwarfarins — brodifacoum, bromadiolone, diphacinone) is a major veterinary emergency. First-generation rodenticides: warfarin (0.005–0.025% in baits); designed to require repeated ingestion for lethality; a single ingestion of a standard bait station by a dog typically does not cause anticoagulant coagulopathy — but dose-dependent risk exists. Second-generation superwarfarins: brodifacoum, bromadiolone, diphacinone in 'all-weather' blocks are far more potent and have much longer durations of action (weeks to months) than warfarin; single-bait-block ingestion can cause severe coagulopathy in dogs lasting 3–6 weeks; treatment requires prolonged vitamin K1 therapy. Relay toxicosis: dogs can be secondarily poisoned by eating rodents that died from superwarfarins — particularly important in hunting dogs and scavenging breeds. Clinical signs: delayed 2–5 days after ingestion; lethargy, dyspnea (hemothorax), pale mucous membranes, epistaxis, hematomas, hematuria, hemarthrosis; PT and APTT markedly prolonged. Treatment: vitamin K1 (phytonadione) 2.5–5 mg/kg/day orally for warfarin (2–4 weeks) or superwarfarins (4–6 weeks); whole blood or plasma transfusion for active hemorrhage; hospitalization for severe cases.
Regulatory consensus
1 regulatory bodyhas classified Warfarin.
| Agency | Year | Classification | Notes |
|---|---|---|---|
| FDA | — | Approved anticoagulant | Approved for prevention and treatment of venous thromboembolism (DVT, PE), atrial fibrillation thromboembolism prevention, mechanical heart valve prophylaxis, and post-MI stroke reduction |
Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.
Where pets encounter warfarin
- Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
- Occupational Environments — Factories, Warehouses, Transportation vehicles
Safer alternatives
Lower-risk approaches that achieve a similar outcome to Warfarin:
-
Alternative drug class; Non-pharmacological therapy; Lowest effective dose
Trade-offs: Direct chemical substitution requires verification that the replacement does not introduce new hazards (regrettable substitution). Conduct full hazard assessment of proposed alternative before adoption.Relative cost: 1.2-2×
Frequently asked questions
Is warfarin safe for pets?
Warfarin and related anticoagulant rodenticides are among the most common causes of fatal canine poisoning; while therapeutic warfarin is rarely used in veterinary medicine today, accidental ingestion of warfarin-based rodenticides (and especially second-generation superwarfarins — brodifacoum, bromadiolone, diphacinone) is a major veterinary emergency. First-generation rodenticides: warfarin (0.005–0.025% in baits); designed to require repeated ingestion for lethality; a single ingestion of a standard bait station by a dog typically does not cause anticoagulant coagulopathy — but dose-dependent risk exists. Second-generation superwarfarins: brodifacoum, bromadiolone, diphacinone in 'all-weather' blocks are far more potent and have much longer durations of action (weeks to months) than warfarin; single-bait-block ingestion can cause severe coagulopathy in dogs lasting 3–6 weeks; treatment requires prolonged vitamin K1 therapy. Relay toxicosis: dogs can be secondarily poisoned by eating rodents that died from superwarfarins — particularly important in hunting dogs and scavenging breeds. Clinical signs: delayed 2–5 days after ingestion; lethargy, dyspnea (hemothorax), pale mucous membranes, epistaxis, hematomas, hematuria, hemarthrosis; PT and APTT markedly prolonged. Treatment: vitamin K1 (phytonadione) 2.5–5 mg/kg/day orally for warfarin (2–4 weeks) or superwarfarins (4–6 weeks); whole blood or plasma transfusion for active hemorrhage; hospitalization for severe cases.
What products contain warfarin?
Warfarin appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments).
See Warfarin in the pets app
Look up products containing warfarin, compare to alternatives, and explore the full data record.
Open in pets View raw API dataSources (2)
- FDA Prescribing Information: Warfarin (Coumadin) — vitamin K antagonist; narrow therapeutic index; bleeding risk; INR monitoring; vitamin K1/PCC antidotes; CYP2C9/VKORC1 pharmacogenomics; many drug-food interactions; DOAC comparison (2023) (2023) — regulatory
- ASPCA Animal Poison Control Center: Anticoagulant Rodenticide Toxicosis — warfarin vs superwarfarins (brodifacoum/bromadiolone); relay toxicosis; prolonged vitamin K1 treatment; coagulopathy signs; PT/APTT; transfusion; 4–6 week treatment duration (2023) (2023) — veterinary
Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →