As rodenticide makers have replaced poisons to meet environmental rules, the Pet Poison Helpline has received more calls about a neurotoxic poison that has no antidote.
Dr. Ahna Brutlag, a veterinary toxicologist who is associate director of veterinary services for SafetyCall International and the Pet Poison Helpline, said treating victims of bromethalin poisoning is more difficult than treating those with anticoagulant poisoning, and the help line received about two-thirds more calls about bromethalin incidents in 2013 than 2011.
“We’ve seen a very sharp increase in the number of bromethalin cases that we’ve been consulted about,” she said.
While vitamin K1 is an antidote for first- and second-generation anticoagulants, pets that have eaten bromethalin typically need multiple doses of activated charcoal and hospitalization, Dr. Brutlag said.
Since 2011, the Environmental Protection Agency has prohibited rodenticide makers from selling second-generation anticoagulants in products marketed for use by the public. One company, Reckitt Benckiser, fought the ban but has agreed to stop selling such products before April 2015 (see article).
In the same time during which bromethalin-related calls increased, Dr. Brutlag said calls about second-generation anticoagulants declined about 8 percent. She expects calls about those poisons will plummet as the remaining products become less available.
The rules affecting second-generation anticoagulants are intended to prevent deaths of predators and scavengers. Second-generation anticoagulants are more toxic than first-generation anticoagulants, yet a lethal dose of the second-generation products can take a week to kill a rodent, which can eat more poison during that time, agency information states. The poison also is more persistent in rodent carcasses than are first-generation anticoagulants.
Most calls to the help line about bromethalin involve products that meet EPA safety standards, which were implemented at the same time as the restrictions on anticoagulants and require that manufacturers sell the products with bait housing for the poisons to reduce the risk that children and pets will eat them.
But Dr. Brutlag said dogs have chewed through the plastic or cardboard retail packages, while others found poison bait distributed outside the protective stations. One pound of rodenticide can be sold, for example, as 16 blocks that come with a single bait station, she said.
A help line study found that dogs that receive early, appropriate treatment for bromethalin poisoning tend to recover well, she said. Even some dogs that had neurologic signs when they arrived at a veterinary clinic largely recovered, although some dogs observed in the study took upward of six weeks to approach normal function.
“It’s not a death sentence by any means,” Dr. Brutlag said. She added that recovery is possible when owners can provide needed care.
The help line does not release call-volume figures, but Dr. Brutlag said the rodenticide-related calls have remained between 5 percent and 7 percent of the help line’s total call volume over the past 10 years.