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My 3 kg cat ate a crumb of anticoagulant rodenticide and now has bloody diarrhea 8 hours later — is this just a tummy upset?

Cats · Emergency guide

Last reviewed: 2026-09-05 · Reference ranges: ASPCA, Pet Poison Helpline & Merck Veterinary Manual

Short answer

No, bloody diarrhea is a sign of internal bleeding, not a simple upset. These poisons block vitamin K, so the cat can't clot blood normally, leading to hemorrhage in the intestines. Even a tiny crumb is enough for a small cat, and signs like pale gums or weakness often appear before the visible blood. This is an emergency — don't wait for more symptoms. Call your vet or an emergency clinic now and tell them exactly what bait was eaten; they'll need to start vitamin K therapy immediately.

Why anticoagulant rodenticides are dangerous

These baits contain compounds such as brodifacoum that block vitamin K recycling, leading to uncontrolled hemorrhage.

Even small amounts can cause internal bleeding that may not be visible at first.

Why speed matters

Delaying care significantly worsens outcomes. Some signs appear hours or days later, so "looks fine right now" is not a reason to wait.

Signs to watch for

  • Lethargy or weakness
  • Pale gums
  • Bruising or bleeding from gums, nose or rectum
  • Vomiting blood or dark stool
  • Rapid heart rate

What to do right now

  1. Call your vet or a pet poison control line immediately
  2. If ingestion was within two hours and the pet is awake, a veterinarian may induce vomiting
  3. Do not give any human medication without veterinary advice
  4. Transport the pet to the clinic for blood work and vitamin K therapy
If your pet shows any of the signs above, go to the nearest emergency vet now and call ahead.

The step-by-step response, from the first minute to the vet visit, is in our Anticoagulant Rodenticide Toxicity in Dogs and Cats emergency guide.

Open the full emergency guide: Anticoagulant Rodenticide Toxicity in Dogs and Cats →

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