Is Brodifacoum safe for dogs and cats?

Brodifacoum is a second-generation anticoagulant rodenticide (SGAR) and the most widely encountered rodenticide cause of death in dogs in the US. Mechanism: competitive inhibition of vitamin K 2,3-epoxide reductase → depletion of vitamin K-dependent clotting factors (II, VII, IX, X, protein C, protein S) → coagulopathy developing 2–5 days after ingestion. The critical danger: there is a clinically silent latent period of 2–5 days between ingestion and the onset of bleeding, during which owners may believe their dog is unaffected. Exposure routes: (1) primary — direct ingestion of bait stations (pellets, blocks, liquid); (2) secondary (relay) poisoning — ingestion of a poisoned rodent, which can contain sufficient brodifacoum in tissues to poison a dog. Clinical signs: spontaneous hemorrhage at any site — gingival bleeding, nasal bleeds, blood in urine/stool, pleural/peritoneal hemorrhage, subcutaneous hematomas, pulmonary hemorrhage. PT/INR dramatically elevated at presentation. Brodifacoum's extremely long tissue half-life in dogs (mean ~120 days) means treatment requires vitamin K1 administration daily for 4–6 weeks minimum, followed by repeat coagulation testing. EPA has required tamper-resistant bait stations for consumer products and restricted pellet formulations; however brodifacoum baits remain widely available. Fatality is common without treatment; excellent prognosis with adequate vitamin K1 duration.

Cats are highly susceptible to brodifacoum toxicosis through primary ingestion of bait and secondary (relay) poisoning from eating poisoned mice. Cats are effective rodent hunters and frequently ingest entire carcasses containing hepatic and tissue brodifacoum concentrations that can cause fatal anticoagulation. Clinical presentation mirrors the dog context — coagulopathy with delayed onset (2–5 days post-exposure). Cats may present with internal hemorrhage (pleural effusion, hemothorax), hematuria, or prolonged bleeding from minor wounds. Diagnosis requires prothrombin time (PT) measurement; INR may exceed 8 at presentation. Treatment: vitamin K1 at 1.5–2.5 mg/kg/day subcutaneously or orally for 4–6 weeks; transfusion if hemorrhagic shock. Brodifacoum's prolonged tissue half-life in cats requires extended treatment durations. Outdoor cats in rodenticide-treated environments (farms, warehouses) are at persistent secondary poisoning risk. EPA restrictions on consumer bait placement do not eliminate this secondary poisoning exposure pathway.