If you have any reason to suspect your pet has ingested something toxic, please contact your veterinarian or one of the other resources listed:
• ASPCA Animal Poison Control Center 24-hour hotline at (888) 426-4435
• Pet Poison Helpline® 24-hour animal poison control service at (855) 764-7661
Warfarin
Generic Name: Warfarin
Brand Name: Coumadin
Warfarin is an anticoagulant used in both human and veterinary medicine. In dogs, it is used primarily for long-term thromboprophylaxis. Current evidence is controversial, but not recommended.
Despite it’s use in veterinary medicine, acute overdosages of warfarin may result in life-threatening hemorrhage.
It’s important to note that a lag time occurs after warfarin is ingested. It could, therefore, take 2-5 days before signs of toxicity occur.
Signs and symptoms of toxicity: extreme fatigue, refusal to eat, bloody urine, and vomiting. Due to the nature of warfarin’s mechanism of action, it may take 2-5 days before signs of toxicity occur. Animals should be monitored accordingly.
Toxic consumption: In both dogs and cats, doses of 5-50 mg/kg have been associated with toxicity. Cumulative toxic doses of warfarin have been reported as 1-5 mg/kg for 5 to 15 days in dogs and 1 mg/kg for 7 days in cats.
| X-Small Yorkie, Chihuahua |
Small Pug, Boston Terrier, Poodle |
Medium Beagle, Scottish Terrier |
Large Boxer, Cocker Spaniel |
X-Large Labrador & Golden Retrievers, German Shepherd |
XX-Large Great Dane, St. Bernard |
| 1 – 10 lbs. (0.45 – 4.6 kg) |
11 – 25 lbs. (5 – 11.4 kg) |
26 – 40 lbs. (11.8 – 18.2 kg) |
41 – 70 lbs. (18.6 – 31.8 kg) |
71 – 90 lbs. (32.3 – 40.9 kg) |
91 – 110 lbs. (41.4 – 50 kg) |
 |
 |
 |
 |
 |
 |
| > 2.25 mg | > 25 mg | > 59 mg | > 93 mg | > 161.5 mg | > 207 mg |
| Most Cats | Large Cats |
| 1 – 10 lbs. (0.45 – 4.6 kg) |
11 – 25 lbs. (5 – 11.4 kg) |
 |
 |
| > 2.25 mg | > 25 mg |
References:
– Papich MG. Saunders Handbook of Veterinary Drugs: Small and Large Animal. 3rd ed. St. Louis, MS: Elsevier Saunders; 2011.
– Warfarin Sodium. In: Plumb’s Veterinary Drugs. Tulsa (OK): Educational Concepts, L.L.C. [updated 8/14; accessed 8/27/15]. https://www.plumbsveterinarydrugs.com/#!/monograph/1721
Pet Poison Control is provided free as a public service by the American College of Veterinary Pharmacists. Today we’re asking you to support us with a small donation. If you would like to dedicate your gift in honor or memory of a pet or individual, you will have that option before checkout. Your gift of any amount helps us maintain this resource and make it available to the pharmacy and veterinary communities. Thank you!
