Rodenticide Poisoning in Cats: Anticoagulants, Internal Bleeding and Antidote

Rodenticide poisoning in cats is one of the most perilous toxicological emergencies encountered in feline medicine. Cats may ingest commercial bait directly or suffer secondary (relay) toxicity after hunting rodents that have ingested lethal baits. While anticoagulant compounds that deplete vitamin K1 are most prevalent, non-anticoagulant baits present rapidly fatal neurotoxic or hypercalcemic crises lacking universal antidotes.

Sources

This guide is not a substitute for a vet.24h Emergency Vets

Veterinarian performing physical and mucous membrane examination on an emergency cat patient — Foto: Nekolife

In this guide

1. Classes of Rodenticides and Toxic Mechanisms

Modern rodenticide formulations fall into distinct mechanistic classes:

First- and Second-Generation Anticoagulants (Brodifacoum, Diphacinone, Warfarin): Inhibit vitamin K1 epoxide reductase, disrupting activation of clotting factors II, VII, IX, and X. Hemorrhage occurs once existing factor pools decay.
Cholecalciferol (Active Vitamin D3): Induces hypercalcemia and hyperphosphatemia, causing extensive tissue mineralization, renal failure, and cardiac arrest.
Bromethalin: Uncouples mitochondrial oxidative phosphorylation in the central nervous system, producing intramyelinic edema, tremors, paralysis, and refractory seizures.
Zinc Phosphide: Releases fatal phosphine gas upon contact with stomach acid.

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2. Primary vs Secondary (Relay) Toxicity in Cats

While dogs frequently gorge on palatable block baits, feline poisonings frequently stem from predatory behavior. A cat consuming a sluggish rodent containing concentrated hepatic residues of long-acting second-generation anticoagulants absorbs a dangerous toxic dose.

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3. Clinical Presentation: The Signs of Uncontrolled Hemorrhage

Because clotting factor degradation takes several days, clinical manifestation is delayed:

Cavity hemorrhage: Hemothorax leading to severe restrictive dyspnea and muffled lung sounds; hemoperitoneum resulting in abdominal distension.
External bleeding: Bleeding from the nose (epistaxis), blood in the urine or stool (melena), and gingival petechiae.
Profound systemic pallor, cold extremities, hypothermia, and hemorrhagic shock.

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4. Diagnostic Triage: Coagulation Profiles and Imaging

Immediate clinical evaluation includes:

Prothrombin Time (PT) and aPTT: PT elongates first due to the short half-life of Factor VII (approx. 6.2 hours in cats), followed by activated partial thromboplastin time.
Baseline PCV and Total Solids: Quantifies the magnitude of internal blood loss.
POCUS (TFAST/AFAST): Rapid thoracic and abdominal ultrasound identifies anechoic fluid pockets (free blood) without repositioning distress.

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5. Treatment Protocol: Vitamin K1 and Plasma Resuscitation

Emergency stabilization depends on timing and toxin category:

Early decontamination (<2-4 hours): Inducing emesis in cats (using alpha-2 agonists like dexmedetomidine) followed by activated charcoal administration.
Phytonadione (Vitamin K1): Standard of care for anticoagulants administered orally with a fatty meal for 21 to 30 days. Note: Vitamin K3 is ineffective and nephrotoxic!
Fresh Frozen Plasma (FFP) or Whole Blood: Immediately restores functional clotting factors in cats experiencing active life-threatening hemorrhage.

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Scientific Sources and References

Peterson, M. E., & Talcott, P. A. (2013). Small Animal Toxicology, 3rd ed. Elsevier.
Waddell, L. S. (2013). Rodenticide toxicities in small animals. Vet Clin North Am Small Anim Pract, 43(5), 1057-1070.
Murphy, M. J. (2002). Rodenticides. Vet Clin North Am Small Anim Pract, 32(2), 469-484.

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