People in the Portland Metro area routinely experience problems with unwanted rodents in or around their homes. Our mild climate and abundance of resources provide excellent habitat for these critters. The most popular method of controlling unwanted rodent populations is using rodenticide (“rat poison”) products; these products are appealingly flavored and contain poison that will kill rodents when ingested. This is a concern for pet owners because the flavor can also be appealing to pets, and the active ingredients in these products are toxic to pets as well as rodents. The most popular of these products is d-Con, though there are many different brands of rodenticide on the market.
Changing Active Ingredients
For the last few decades, d-Con’s active ingredient was an anticoagulant, but recently this changed to cholecalciferol (vitamin D3). This was in response to EPA regulations which were changed to allow three different types of active ingredients; a short-acting anticoagulant different than what was in original d-Con, bromethalin (a neurotoxin with no antidote), or cholecalciferol. While the short-acting anticoagulants are safer, they are also less effective, and since bromethalin poses a serious threat to children, d-Con opted to change their active ingredient to cholecalciferol. Other brands of rodenticide may have chosen any of the currently allowable options.
While there is treatment for anticoagulant toxicity in pets, neither bromethalin nor cholecalciferol have an antidote. Prior to this change, if a pet ingested a rodenticide and the product packaging was not available, the veterinarian could generally assume that the active ingredient was an anticoagulant. Anticoagulant treatment is generally effective and straightforward. That has now changed; if a pet ingests a rodenticide and the pet owner does not have the product’s packaging available, the active ingredient could be an anticoagulant (old or new, depending on the age of the product), bromethalin, or cholecalciferol. Since treatment options for bromethalin and cholecalciferol are very limited, whereas anticoagulant treatment is straightforward, this poses a major problem for veterinarians and pet owners.
Why is vitamin D toxic? People take it as a supplement
Vitamin D3 is an essential vitamin for people as well as dogs and cats, however, large doses are toxic, causing acute kidney failure within 2-3 days. In dogs and cats, it takes only a small amount of vitamin D3 to cause toxicity. Compounding this problem, signs, and symptoms of cholecalciferol poisoning may not appear for 1-2 days after exposure, and by this time significant and irreversible damage has likely already occurred. Immediate treatment post-ingestion is crucial to preventing permanent, or even fatal, consequences.
What can I do?
The most important thing is to keep your rodenticide products, bait-stations, and traps away from where pets can access them. Even “pet-proof” packaging and bait-stations can be breached by a motivated pet, which is something we and the Pet Poison Control Center experience all the time. It is equally important to talk to your neighbors about what products they use and where, and also find out if your neighbors or neighborhood HOA use a pest control company. We often have cases where a pet ingests poison because a neighbor is using rodenticide, unknown to the pet owner.
A word on wildlife
Anticoagulant rodenticide is a major threat to wildlife through secondary poisoning. All wildlife who consume rodents as food are at risk; owls, hawks, foxes, coyotes, raccoons, bobcats, etc, and even pet cats and dogs who hunt. As these natural predators consume rodents who have been poisoned, the toxins accumulate in their bodies until they themselves are poisoned. The shift from anticoagulants to Vitamin D3 is potentially safer for wildlife, though further study must be performed. Poisoning of owls and other birds of prey is a significant concern to wildlife advocates, like our own Dr. Peterson, who volunteers with the Chintimini Wildlife Center. These birds are our natural rodent control, so if you are considering removing rodents from your property, please do some research about methods that are safer for our native wildlife. For more information, this article from the Audobon society is an excellent resource.