By Ahna Brutlag, DVM, MS, DABT, DABVT
Associate Director of Veterinary Service, Pet Poison Helpline
New EPA mandates concerning rodenticides were released in 2011, which spurred the manufacturer of d-CON, the largest selling rodenticide in the US, into heated battle with the Agency. In short, this has left the current rodenticide market in flux and has presented a challenge to veterinarians trying to treat potentially poisoned patients.
In effort to reduce relay or secondary poisoning in wildlife, EPA banned the use of second generation anticoagulant rodenticides (SGARs) for household use leaving manufacturers the option of using bromethalin (a potent neurotoxin), first generation anticoagulants (e.g., warfarin), and cholecalciferol (Vitamin D3). EPA argued that SGARs pose too great a threat to wildlife due to their increased toxicity over first generation anticoagulants and ability to bioaccumulate in the livers of predators. The d-CON company primarily uses brodifacoum, an SGAR, as their primary active ingredient. They refuted EPA’s argument stating that the ban on SGARs would lead to increased bromethalin (neurotoxicant) use, thereby increasing the risk of poisoning to pets and children due to the potency and lack of antidote. While the legal battle raged on, d-CON was allowed to continue sales of its SGAR product.
As predicted, bromethalin, a neurotoxicant which causes cerebral edema and has no antidote, has become the active ingredient of choice by compliant rodenticide manufacturers. This has been especially concerning for veterinarians who want to know how to properly identify and treat this new poison as reflected by a 65% increase in bromethalin cases reported to Pet Poison Helpline since 2011. Toxic ingestions of bromethalin often require multiple doses of activated charcoal over 24 hours. If cerebral edema develops, intensive care may be required for several days. Due to the prolonged half-life of the toxicant and slow healing process of the CNS, clinical signs may persist for weeks or become permanent.
On May 30, 2014, d-CON announced that it will comply with EPA mandates by replacing brodifacoum with diphacinone, a first generation anticoagulant. While many first generation anticoagulants, such as the prototype warfarin, are shorter acting, diphacinone is not. Veterinarians are still advised to treat patients for 3-4 weeks with Vitamin K1.
To learn more about the clinical signs, treatment, and diagnosis of rodenticide poisoning, veterinary professionals may watch Pet Poison Helpline’s educational webinar Rodenticides: It’s more than just Vitamin K! (recorded live on June 10, 2014). Viewers receive 1 hour of NYSED and RACE-approved, non-interactive continuing education credit. View the webinar at www.petpoisonhelpline.com on the For Vets page.