These factors are present in a nonfunctional form and are converted by active vitamin K1 into functional coagulants. It is needed to activate K-dependent coagulation factors prothrombin (II), proconvertin (VII), antihaemophilic factor B (IX) and Stuart factor (X). Vitamin K1 is supplied through dietary intake and production by gut bacteria. Coumatetralyl was demonstrated to have a plasma elimination half-life of 0.52 days following a single oral dose compared to Brodifacoum, a secondgeneration product, which showed a plasma elimination half-life of 91.7 days.1 The elimination half-lives in liver varied from 15.8 days for coumatetralyl to 307.4 days for brodifacoum. These so called “superwarfarins” persist in the body for some time – up to eight weeks or longer in the case of the third generation compounds. Second generation anticoagulants include diphacinone, difenacoum and bromadiolone and third generation products include brodifacoum and ocoumafen. These usually require higher doses to be consumed and repeated consumption over consecutive days is necessary to exert toxic effects in rodents. First generation anticoagulants include coumafen (warfarin) and coumatetralyl. Concentrates are generally reserved for professional use but coated cereals, bait blocks, baited traps, waxed “scatter packs”, sachets and semolina formats are freely available with some even boasting “professional strength” formulas. There are over 500 types of anticoagulant rodent poisons in use across Europe. The availability of appropriate treatments has also proved problematic until quite recently.

Therapy is often complicated by uncertainty over the likelihood of exposure, the time that has elapsed since the anticoagulant was consumed and the dose ingested.

ACCORDING to the Veterinary Poisons Information Service (VPIS), well over 1,000 telephone enquiries are received each year from UK veterinary professionals seeking advice on how to manage potential and accidental exposures to anticoagulant rodenticides in a variety of animals – mainly pet dogs.

Antidote for vitamin k toxicity