Administration of
vitamin K1, SC, to
anticoagulant-poisoned (
diphenadione) dogs provided diagnostic information within 4 hours, when
vitamin K1 and its
epoxide were measured in canine sera. Twelve dogs (2 groups of 6) were given 2.5 mg of
diphenadione/kg of
body weight for 3 days. Dogs were treated with
vitamin K1, 2.5 (n = 6) or 5 mg/kg/day (n = 6) SC for 21 days, and their responses were compared. Four nonexposed control dogs were given 5 mg of
vitamin K1/kg/day. Serum concentration of
vitamin K epoxide was significantly (P less than 0.02) higher in
diphenadione-exposed dogs than in control dogs 1 to 4 hours after the initial
vitamin K1 treatment on day 4.
Vitamin K epoxide/
vitamin K1 ratios were similarly higher and became more distinct. Cessation of
vitamin K1 therapy on day 24 resulted in prolongation of one-stage prothrombin times in
diphenadione-exposed dogs, becoming clearly evident on day 27. Serum
vitamin K1 concentrations were not detectable on day 27 in
diphenadione-exposed dogs, whereas serum
vitamin K1 concentrations were readily detectable in control dogs. One-stage prothrombin time changes, during days 24 to 32, indicated 5 mg of
vitamin K1/kg provided better protection than did 2.5 mg of
vitamin K1/kg. Coagulopathy in the dogs was resolved by day 32.