Antifreeze (ethylene glycol) is well known to be an extremely hazardous substance if ingested by dogs and cats. If veterinary treatment is not begun within a few hours of exposure, one teaspoonful of ethylene glycol can be fatal to a 10-pound cat, while one to two tablespoonfuls can kill a 10-pound dog. A less toxic form of antifreeze, propylene glycol, is safer than ethylene glycol, but it can still cause poisoning if consumed in large enough quantities. The problem of toxicity is exacerbated by the fact that animals may be attracted to antifreeze. The ASPCA and other agencies have attempted to educate the pet guardians about the dangers of antifreeze. Nevertheless, pets—especially dogs—continue to be exposed each year.
To protect pets and people from antifreeze poisoning, product manufacturers as well as some humane groups propose adding a bitter, taste-aversive agent such as denatonium benzoate (Bitrex®) to ethylene glycol-containing automobile antifreeze, and federal legislation has been proposed to this effect. While the ASPCA supports the concept of protecting companion animals from known poisons through taste aversion, there is as yet no published data demonstrating the efficacy of Bitrex, or any other taste-aversive substance, in the dog. In fact, The ASPCA’s Animal Poison Control Center regularly receives calls involving dogs who have consumed mouse poison containing denatonium benzoate.
The ASPCA’s Animal Poison Control Center and dog guardians are well aware of the fact that dogs will eat unlikely substances in alarming quantities. The ASPCA is concerned that antifreeze containing a taste-aversive substance specifically added to protect dogs would be marketed as “safer,” thus causing pet guardians to be less vigilant with regard to handling and storing this potentially lethal product. In the meantime, the ASPCA is on the front lines working with Paladin Labs (USA), Inc., the company that manufactures Antizol-Vet®, an antidote for ethylene glycol antifreeze poisoning in dogs, to keep life-saving medical care and advice available.
At this time, the ASPCA is neutral on legislation requiring the addition of taste-aversive agents such as denatonium benzoate (Bitrex) to automobile antifreeze products containing ethylene glycol for the purpose of preventing poisoning in animals. The ASPCA believes that research is necessary to determine if Bitrex or other taste-aversive agents reliably deter dogs. Such data does not exist. If the proposed legislation passes, the ASPCA recommends that its implementation include additional public education on the dangers of antifreeze poisoning, and that manufacturers continue to monitor the frequency and outcomes of antifreeze incidents.