Why half a block is critical for a 2.5 kg cat
A cat this small lacks the body mass to buffer even moderate doses of anticoagulant rodenticides. The active ingredients in most blocks—like brodifacoum—are designed to kill rodents many times larger than your pet. What looks like "half" to you could be several lethal doses for a feline, as their liver processes these toxins far slower than a rat's would.
Unlike immediate poisons, this type causes delayed bleeding by depleting vitamin K-dependent clotting factors. Your cat might seem fine for days before weakness, labored breathing, or pale gums appear. By then, internal hemorrhage could already be severe. Don't wait for these signs—emergency care now can administer vitamin K and prevent irreversible damage.
The silent danger of second-generation anticoagulants
Modern rodenticides are "second-generation," meaning they're engineered to be deadlier with smaller amounts. They bind tightly to liver enzymes and can't be flushed out quickly. For perspective: a single feeding might require weeks of vitamin K therapy in pets, whereas older formulas needed larger repeated doses.
Your cat's grooming habits add risk—even if they didn't swallow all the chewed material, licking residue from their paws introduces more poison. The vet may recommend blood tests to check clotting times (PT/PTT) and baseline organ function before symptoms emerge.
Why inducing vomiting isn't enough
Some owners assume making the cat vomit solves the problem, but anticoagulants absorb rapidly through mucous membranes. Chewing the block means the gums and tongue already absorbed some toxins before swallowing. Vomiting might remove stomach contents but won't reverse what's in the bloodstream.
Hospital monitoring is crucial because clotting times peak 36–72 hours after ingestion. Your vet will likely start injectable vitamin K1 immediately, then transition to oral doses for 3–4 weeks. Without this, delayed bleeding can occur even if the cat seemed fine post-vomiting.
Special risks for petite felines
Small cats have less blood volume to lose before showing shock signs. A 2.5 kg cat losing just 30–40 ml internally (about two tablespoons) can become critically anemic. Their high metabolism also processes toxins faster than larger animals, sometimes accelerating symptom onset.
Watch for subtle changes like reluctance to jump (indicating joint bleeding), tarry black stools (digested blood), or swollen joints. These warrant immediate ICU care—transfusions may be needed to replace lost blood cells while the anticoagulant effects are reversed.
The step-by-step response, from the first minute to the vet visit, is in our Rat Poison (Rodenticide) Poisoning emergency guide.