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WARNING: Rodent Poisons Containing Bromethalin are Deadly for Cats and Dogs

Jun 19, 2017

Do you or your neighbors use rodenticide (mouse and rat poison)? Here’s something to think about—your dog or cat may also be at risk! Rodenticides containing bromethalin severely impair the neurologic functions of animals. What makes this over-the-counter rodenticide so dangerous is that there is no antidote, meaning, there is no specific treatment designed to counteract the effects of the poison once it begins to affect the body.

Warning Signs

Cats poisoned by bromethalin develop rapidly deteriorating neurologic symptoms. Unfortunately, once these signs develop, most cats do not survive. These symptoms include:

  • Weakness
  • Wobbling and incoordination
  • Dullness
  • Seizures
  • Coma
  • Death

Bromethalin is a poison that causes fluid to abnormally accumulate in the brain and spinal cord, causing severe swelling of these tissues. This swelling results in the neurologic symptoms described above. The best diagnostic imaging test to detect this swelling is MRI.

Though bromethalin poisoning has no antidote, there is a very short window of time to try to block the toxin from being absorbed by the body after it is eaten. Time is of the essence to seek medical attention.


The best cautionary measure is to avoid using rodenticides in and around your home, especially if they contain bromethalin, and to supervise outdoor cats if they are prone to hunting. Cats can be exposed to the poison by eating it directly or by eating mice or rats who have already ingested the toxin. Once the toxin is ingested, mice or rats cannot move normally, thus making them easy prey for inquisitive cats, as well as birds that feed on rodents. Only small amounts of bromethalin are required to cause toxicity leading to death.

If Your Pet Has Ingested Rodenticide

It is important to note that all rodenticides are toxic to animals — including those using active ingredients other than bromethalin. Until recently, treatment options were available for pets exposed to previous generations of rodenticide ingredients. However, this more recent generation of rodenticide containing bromethalin is especially dangerous because there is no antidote.

If you believe your pet may have been exposed to rodenticides of any kind, it is critical to do the following:

  • Immediately bring your pet to a veterinarian for an emergency evaluation
  • Bring along any remaining rodenticide (including packaging) that you can quickly find
  • Safely secure this toxin out of reach of your pet during travel to the hospital

Pet Poison Prevention & Emergency Contacts

Curious pets have been known to get into things they shouldn’t. Pet proof your home as much as possible to avoid inadvertent toxin exposure. In general, if you think your pet has ingested any hazardous substances, including home and garden products, human food and medications, poisonous plants, or other harmful objects, please contact your veterinarian, your local veterinary emergency hospital, or the ASPCA’s 24-hour emergency poison hotline at 1-888-426-4435. Keep these phone numbers in a convenient, easy to find place at home. For a comprehensive list of hazards and toxins, visit


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