Trainers are warned to take precautions when using rat and mouse baits in and around stable premises. The active ingredients of these baits are anticoagulant rodenticides, namely warfarin, brodifacoum, bromadiolone and difenacoum. All of these chemicals would be considered to be prohibited substances according to the Australian Rules of Racing and are capable of being detected in blood and urine samples from horses.
Apart from being prohibited substances, these anticoagulant rodenticides also pose the threat of toxicity in horses that ingest them. A small cluster of deaths in racehorses due to unusual haemorrhagic conditions has been reported by the California Horse Racing Board (CHRB) through their necropsy program in collaboration with the University of Davis. Traces of anticoagulant rodenticides were found in the livers of a small number of horses identified with unusual haemorrhage during necropsy. Even though the levels of anticoagulant rodenticides were well below what is generally considered necessary to induce toxicity, there is the concern that the high blood pressures in horses associated with the exertion of racing and training may reduce the toxicity threshold.
Therefore, trainers are advised to take precautions against the accidental ingestion of rodenticides by horses arising from the use of these poisons in and around racing stables. Such ingestion may be due to inadvertent contamination of feedstuffs with the poisons or rodent droppings containing them.