Rat poison eliminates rodent populations as a pest control measure. Formulated to be appealing, these substances contain highly toxic active ingredients. Different types of rat poisons employ distinct biological methods, targeting fundamental physiological processes to achieve their lethal effect.
Disrupting Blood Clotting
One common type of rat poison, known as anticoagulant rodenticides, interferes with blood clotting. Compounds like warfarin, brodifacoum, and bromadiolone belong to this category, acting as vitamin K antagonists. These substances disrupt the vitamin K cycle, a biochemical pathway for regenerating active vitamin K. Vitamin K is necessary for the liver to produce several blood-clotting factors, including factors II, VII, IX, and X.
Anticoagulant rodenticides primarily inhibit vitamin K epoxide reductase (VKOR), an enzyme that converts inactive vitamin K epoxide into its usable form. Without this enzyme functioning properly, the body depletes its supply of active vitamin K. This depletion prevents the liver from synthesizing new, functional clotting factors. Consequently, the affected animal’s blood loses its capacity to clot effectively.
This impairment leads to widespread internal bleeding throughout the body. Blood can leak from the smallest vessels, and even minor injuries can result in significant blood loss. Accumulated blood in tissues and organs, combined with reduced circulating blood volume, eventually causes shock, organ failure, and death. The effects are typically delayed, with clinical signs appearing several days after ingestion as existing clotting factors are used up.
Inducing Calcium Overload
Another rat poison category uses cholecalciferol (Vitamin D3) to induce a lethal calcium imbalance. Ingested in high doses, cholecalciferol is metabolized, leading to excessive calcium absorption from the intestines. It also mobilizes calcium from the bones, significantly increasing calcium levels in the bloodstream. This condition, known as hypercalcemia, overwhelms the body’s regulatory systems.
The elevated calcium concentrations cause calcium to deposit in soft tissues throughout the body. This calcification particularly affects organs such as the kidneys, heart, and blood vessels. The deposition of calcium interferes with the normal function of these organs. This progressive damage ultimately leads to kidney failure, heart dysfunction, and widespread tissue damage, resulting in the animal’s death.
Targeting the Nervous System
Bromethalin-based rodenticides target the nervous system. Once ingested, bromethalin is metabolized in the liver into a more potent compound called desmethylbromethalin. This active metabolite travels to the central nervous system (brain and spinal cord). Here, it interferes with a fundamental cellular process known as oxidative phosphorylation.
Oxidative phosphorylation is essential for cells to produce adenosine triphosphate (ATP), the body’s primary energy currency. By uncoupling this process, bromethalin significantly reduces ATP production, particularly in brain and spinal cord cells. The lack of sufficient ATP disrupts the function of ion pumps, such as the sodium-potassium ATPase, which are responsible for maintaining fluid balance within nerve cells. This disruption leads to fluid accumulation, causing brain swelling. Increased pressure damages nerve axons, impairing neurological function, leading to paralysis and eventual death.
Generating Toxic Gas
Zinc phosphide-based rodenticides generate a highly toxic gas within the animal’s digestive system. When ingested, zinc phosphide reacts with the stomach’s acidic environment. This chemical reaction produces phosphine gas (PH3). The presence of food in the stomach can increase the rate of this reaction, intensifying the toxicity.
The phosphine gas is rapidly absorbed from the stomach and intestines into the bloodstream. Once in circulation, phosphine gas interferes with cellular respiration, particularly affecting cellular mitochondria. It inhibits cytochrome c oxidase, a key enzyme in the electron transport chain necessary for cellular energy production. This inhibition leads to rapid cellular energy production failure and widespread cellular dysfunction. The systemic effect quickly causes multi-organ failure, impacting the heart, lungs, and liver, leading to rapid death.