Bromethalin Rodenticide Poisoning in Cats

What is bromethalin rodenticide poisoning?

Bromethalin is one of the most common types of rodenticides currently on the market. It is found in several forms, including hard blocks, soft baits, pellets, worms or grubs, and meal or grain.

Cats are commonly poisoned when they find loose bait placed for rodent control. Relay toxicity, in which poisoning occurs when an animal ingests rodents that died from bromethalin, has been anecdotally reported in cats.

Once ingested, bromethalin is rapidly absorbed from the gastrointestinal (GI) tract and metabolized in the liver to its more toxic form. The primary target for bromethalin and its metabolite is the central nervous system (CNS). 

It causes depletion of energy in the CNS, ultimately resulting in swelling of various areas of the CNS, including the brain (cerebral edema), leading to severe neurologic signs. Clinical signs can develop as soon as a few hours after exposure and as long as five to seven days after exposure.

What are the clinical signs of bromethalin poisoning?

Cats are more sensitive to bromethalin and develop toxicity at lower doses than dogs. Also, unlike dogs, cats develop common signs at any toxic dose. Clinical signs include:

• Depressed mental activity
• Anorexia
• Vomiting
• Ataxia (impaired muscle control or coordination)
• Decreased intestinal motility
• Pelvic limb weakness that progresses to paralysis
• Tremors, seizures, abnormal body positioning, and coma can develop as the poisoning progresses

How is bromethalin poisoning treated?

There is no antidote for bromethalin, so early decontamination is extremely important. If a cat ingests a toxic dose of bromethalin, prompt decontamination by a veterinarian can be lifesaving. There are no safe ways to induce vomiting in cats at home. Intravenous fluids are delivered to maintain hydration and close electrolyte monitoring is important to watch for elevated sodium levels. If clinical signs develop, additional medications and treatment are initiated to decrease cerebral edema. Clinical signs are then treated as needed.

What is the prognosis for bromethalin poisoning?

Unfortunately, prognosis is poor to grave if severe clinical signs develop, such as seizures, paralysis, or coma. Patients with milder clinical signs may recover after several weeks but may have permanent neurologic damage. If clinical signs can be appropriately managed but there is no improvement after a week, prognosis is poor.

If you suspect or witness your pet ingesting rodenticide, call Pet Poison Helpline, a 24/7 animal poison center, at 1-855-764-7661 and take your pet to a veterinarian for treatment. 

Pet Poison Helpline, an animal poison control center based out of Minneapolis, MN, is available 24/7 for pet owners and veterinary professionals that require assistance treating a potentially poisoned pet. The staff provides treatment advice for poisoning cases of all species, including dogs, cats, birds, small mammals, large animals, and exotic species. As the most cost-effective option for animal poison control care, Pet Poison Helpline’s per-incident fee includes follow-up consultations for the duration of the poison case. Pet Poison Helpline is available in North America by calling 800-213-6680. Additional information can be found online at www.petpoisonhelpline.com.