Effect of three loading doses of warfarin on the international normalized ratio for dogs.
OBJECTIVE
To evaluate effect of 3 loading doses of warfarin sodium on the international normalized ratio (INR) for dogs.


METHODS
18 dogs weighing between 25 and 30 kg.


METHODS
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
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.
Monnet
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E
Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins 80523, USA.
Morgan
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MR
D000284:Administration, Oral; D000818:Animals; D000925:Anticoagulants / Q000008:administration & dosage* / Q000627:therapeutic use; D004285:Dogs / Q000097:blood*; D007083:Iliac Artery / Q000601:surgery; D010314:Partial Thromboplastin Time / Q000662:veterinary; D011517:Prothrombin Time / Q000662:veterinary; D011897:Random Allocation; D012016:Reference Values; D014859:Warfarin / Q000008:administration & dosage* / Q000627:therapeutic use
D000925:Anticoagulants; D014859:Warfarin