PLASMA SUPERWARFARIN LEVELS AND VITAMIN-K-1 TREATMENT IN DOGS WITH ANTICOAGULANT RODENTICIDE POISONING

The plasma concentration, plasma half-life (t(1/2)), and mean residenc e time (MRT) of rodenticide anticoagulants were determined in 21 dogs in which a preliminary diagnosis of anticoagulant rodenticide poisonin g had been made. Brodifacoum, difethialone, and difenacoum were detect ed by high-performance liquid chromatography (HPLC) in the plasma of 1 3, 3, and 2 dogs, respectivery. At presentation the plasma concentrati on ranged from below the detection limit (10 ng/L) to 851 ng/L. Toxin could not be detected in 3 dogs, despite these animals showing charact eristic coagulation disturbances and a positive response to therapy wi th vitamin K-1. In 7 dogs the estimated t(1/2) of brodifacoum ranged f rom 0.9 to 4.7 (median 2.4) days with a MRT of 1.9 to 3.7 (median 2.8) days. In 2 dogs the individual t(1/2) Of difethialone was 2.2 and 3.2 days and the MRT was 2.3 and 2.8 days, respectively. Two dogs died du ring emergency treatment. Treatment in the remaining 19 dogs consisted of the administration of vitamin K-1 and supportive therapy. The dose of vitamin K-1 was reduced in a stepwise manner as long as the prothr ombin time remained within physiological limits. The variation in init ial plasma concentrations of the anticoagulants combined with the resu lts of treatment support the idea that an individual therapeutic appro ach is warranted.