Key result
Warfarin 6 mg/d loading increases INR and PT more than lower doses without bleeding in dogs.
Why the study?
The effect of different loading doses of warfarin on the international normalized ratio in dogs was not well characterized.
Does a 6 mg loading dose of warfarin safely increase INR compared to 2 mg or 4 mg in dogs after bilateral iliac artery grafting?
RCT (n=18)
randomly allocated
Does a 6 mg loading dose of warfarin safely increase INR compared to 2 mg or 4 mg in dogs after bilateral iliac artery grafting?
A 6 mg/day loading dose of warfarin for 2 days safely achieves anticoagulation in dogs weighing 25-30 kg without clinical bleeding.
Small canine study of warfarin dosing is hypothesis-generating; does not support practice change.
OBJECTIVE: To evaluate effect of 3 loading doses of warfarin sodium on the international normalized ratio (INR) for dogs. ANIMALS: 18 dogs weighing between 25 and 30 kg. PROCEDURE: Dogs were randomly allocated into 3 groups and received 2, 4, or 6 mg of warfarin administered orally once a day for 2 days after surgery for bilateral iliac artery grafting. Activated partial thromboplastin (APTT) and prothrombin times (PT) were measured before and after treatment. Prothrombin time also was reported as an international normalized ratio. RESULTS: The APTT were not significantly different among groups before or after treatment. The INR and PT were significantly increased in all groups after treatment. The INR and PT of the 6-mg group were significantly greater than those of the 2-mg and 4-mg groups. None of the dogs had clinical evidence of bleeding. CONCLUSIONS AND CLINICAL RELEVANCE: A warfarin loading dose of 6 mg/d can be safely administered for 2 days to dogs weighing between 25 and 30 kg. Anticoagulation can be achieved safely in dogs in 2 days by use of warfarin. The effects of warfarin can be monitored with the INR.
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Monnet et al. (2000) conducted an RCT in post-surgery for bilateral iliac artery grafting (n=18). Warfarin sodium vs. Different doses (2 mg, 4 mg, 6 mg) was evaluated on International normalized ratio (INR) and prothrombin time (PT). A warfarin loading dose of 6 mg/d for 2 days significantly increased INR and PT compared to 2-mg and 4-mg doses in dogs, with no clinical evidence of bleeding.
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