Rodent Bait (Bromethalin) Poisoning in Cats

Bromethalin is only one of several specific types of poison commonly sold, so correct identification of any poison a cat is exposed to is critical for successful management of poisoning cases in pets.

The blocks or pellets of commonly used rodenticides are often dyed green, regardless of the type of poison they contain so the color of the bait is not helpful in determining specifically what a cat may have ingested. Bromethalin toxicosis is entirely different from the poisoning that results from ingestion of other types of poison, so specific identification of any pellets or blocks is critical to managing the intoxication.

In many cases, the only symptom of bromethalin toxicosis is sudden death, particularly in a cat who goes outside or roams.

The severity of bromethalin toxicity depends on the amount of poison consumed.

Signs of bromethalin toxicosis typically begin within 2-24 hours following ingestion. Larger doses are associated with earlier onset of symptoms. Small doses may take days to produce symptoms.

Cats with a known history of consuming bromethalin poisons have the best prognosis. Immediate veterinary care allows for the toxin to be removed, preventing development of symptoms. These cats have a fair to good prognosis, and require several days of treatment.

Once a cat develops symptoms of toxicity, the prognosis is poor. Aggressive treatment is required, and recovery takes up to several weeks. Many cats have long-term neurologic damage.

Bromethalin toxicosis is rare in cats. Cats that have eaten any amount of bromethalin poison require immediate veterinary care. Cats who ingest a dangerous amount of bromethalin have a fair to good prognosis if treated right away after ingestion and before symptoms develop. Once symptoms have developed, the prognosis is poor, even with aggressive and lengthy treatment. Cats that recover often have permanent neurologic deficits.

The blocks or pellets of commonly used rodenticides are often dyed green, regardless of the type of poison they contain so the color of the bait is not helpful in determining specifically what a cat may have ingested. Bromethalin toxicosis is entirely different from the poisoning that results from ingestion of other types of poison, so specific identification of any pellets or blocks is critical to managing the intoxication.

Most publicly available baits are concentrated enough that treatment is indicated any time an average-sized healthy cat ingests even a small quantity of bromethalin-based products. As little as half an ounce of rodenticide is potentially a lethal dose. Not all bromethalin rodenticides contain the same concentration of active ingredient, so it’s possible for a cat to be poisoned after eating even less than that. Since bromethalin is such a potent toxin and there is no antidote, emergency veterinary care is indicated whenever a cat ingests any amount of bromethalin bait.

Compared to other types of rodent poisons, the chance of a cat eating a toxic dose of bromethalin by consuming a single dead rodent is significantly lower. The only way it’s likely for a cat to experience relay toxicosis with bromethalin is when the cat habitually eats poisoned rodents over time.

Outdoor cats are at the highest risk of bromethalin poisoning. Indoor cats living in households where bromethalin is stored are also at risk.

Bromethalin toxicosis is caused by oral ingestion of bromethalin-based rodenticides. Rodenticides are sold and used as pest control against rodents.

Bromethalin is a neurotoxin, meaning it disrupts normal functioning of the brain and spinal cord.

Diagnosis of bromethalin toxicity is extremely difficult without a history of possible rodent poison exposure. There are no specific tests for bromethalin toxicity in live animals. There is also no specific antidote or treatment for bromethalin toxicity.

If the cat is known to have consumed bromethalin rodent poison within the last 4 hours, vomiting is induced to remove the poison before it is absorbed into the bloodstream. Inducing vomiting must be performed by a veterinarian, as there are no safe at-home methods to induce vomiting in cats. After vomiting, activated charcoal is administered to bind any remaining toxin within the stomach. Administration of activated charcoal should only be performed by a veterinarian. It is not safe to administer activated charcoal without veterinary guidance.

By the time cats develop symptoms, it is too late to prevent absorption of the toxin from the digestive tract. These cats require aggressive treatment in an effort to save their lives.

Treatments in these cases include:

• Diuretics to reduce brain swelling
• Anti-seizure medications
• Muscle relaxants
• Decontaminating medications given directly into the bloodstream

Patients with symptoms are unable to eat. In many cases, a feeding tube is required to maintain nutrition during treatment.

Rodenticide poisoning is not contagious. It is prevented by eliminating access to bromethalin. Many forms of poisoning in pets can be prevented by keeping household chemicals and pesticides secured and out of reach.

Providing an indoor only lifestyle or supervising outdoor play also helps prevent rodenticide poisoning. Cats who are allowed to roam are at the greatest risk of exposure to rodenticides.

All types of rodenticide toxicoses are rare in cats, but bromethalin is widely used in common rodenticides.

• Inducing vomiting
• Activated charcoal
• Diuretics
• Anti-seizure medications
• Muscle relaxants