Six hours is the number that matters after a cat eats rodenticide, and the package in your hand is worth more than any symptom you can describe. Three classes of bait behave completely differently: one bleeds the cat out over 2 to 7 days, one wrecks the kidneys through calcium in 12 to 36 hours, and one swells the brain within 30 minutes to 24 hours.
Two rules apply to all three: bring the box, bag or bait station with you, and do not make the cat vomit at home. Vomiting is a clinic decision made with the product name, the weight of the cat and the time since ingestion in front of them.
The 3 classes, and what each one does
Class 1, anticoagulants. Second-generation compounds such as bromadiolone, brodifacoum and difenacoum block vitamin K recycling, so clotting factors 2, 7, 9 and 10 fade over 24 to 72 hours. The cat looks normal for 2 to 5 days, then bleeds from the gums, passes black stool, or develops a 3 to 5 cm swelling on the flank. A single 0.005 percent bait block of 20 g can carry enough active ingredient to matter for a 4 kg cat.
Class 2, cholecalciferol, which is vitamin D3. Onset is 12 to 36 hours. It pulls calcium out of bone, serum calcium climbs, and the kidneys mineralize. First signs are drinking 2 to 3 times the normal volume, urinating more, then vomiting at 24 to 48 hours. Blood work shows calcium above 12 mg/dL, phosphorus rising, and creatinine up within 48 hours.
Class 3, neurotoxins. Bromethalin uncouples oxidative phosphorylation and causes brain edema in 2 to 24 hours; tetramine and fluoroacetamide, both banned but still found in unregistered baits, cause convulsions within 30 minutes to 4 hours; zinc phosphide releases phosphine gas in the stomach and gives a garlic smell to the breath. Seizures, tremors, ataxia and hyperthermia are the picture, and there is no antidote for bromethalin.
| Class | Common actives | Onset (hours) | Main damage | Key test at 6 h |
|---|---|---|---|---|
| 1 Anticoagulant | bromadiolone, brodifacoum, difenacoum | 24 to 72, up to 120 | bleeding, 2 to 5 day delay | PT and APTT, repeat at 48 h |
| 2 Cholecalciferol | vitamin D3 bait, 0.075 percent | 12 to 36 | hypercalcemia, kidney injury | ionized calcium, phosphorus, creatinine |
| 3a Neurotoxin | bromethalin | 2 to 24 | brain edema, no antidote | neuro exam, temperature |
| 3b Neurotoxin | tetramine, fluoroacetamide, zinc phosphide | 0.5 to 4 | seizures, phosphine gas | glucose, temperature |
Why the 6-hour line exists
Hour 0 to 2: decontamination is most effective. Most vets will induce vomiting if the cat is alert and under 2 hours out, then give activated charcoal at 1 to 2 g/kg. Every 30 minutes past hour 1 lowers the yield.
Hour 2 to 6: the stomach is empty but the toxin is in the gut. Charcoal still binds what is left, and a baseline blood sample taken at hour 6 becomes the reference for every later comparison. Hour 6 is also when a cat that ate a neurotoxin starts to show tremor or a change in pupil size.
Hour 6 to 24: anticoagulant cases still look fine, and that is the trap. A normal PT at hour 6 does not close the case; the standard plan repeats PT at 48 and 72 hours, because factor levels keep falling for 2 to 5 days.
Day 2 to day 7: the late bleed window. A cat that seemed fine and now has pale gums at day 4 needs plasma or whole blood plus a vitamin K1 course measured in weeks, not days. The dose and the length are set by the vet from the PT result and the product, and no owner should be calculating either at home.
Bring the packaging, not a description
Photograph 5 things before you leave the house: the front of the box, the active ingredient panel, the concentration line, the batch number, and the bait itself next to a coin for scale. Then put the box in a bag and bring it.
The clinic needs 4 numbers off that packaging: active ingredient, concentration in percent, bait weight per block, and the number of blocks missing. With a 4 kg cat, 1 missing 20 g block at 0.005 percent is a very different case from 5 missing blocks at 0.075 percent.
Also write down 3 facts: the time you last saw the cat normal, the time you found the chewed block, and whether the cat has vomited. Those 3 timestamps decide whether decontamination is still on the table.
Why you must not induce vomiting at home
First, the class may be a neurotoxin. A cat that is already ataxic or twitching will aspirate vomit into the lungs, and aspiration pneumonia in a 4 kg cat can be fatal on its own.
Second, the household methods are unsafe in cats. Hydrogen peroxide at 3 percent is poorly tolerated by cats and causes stomach irritation at small volumes; salt water can drive sodium up and cause tremors that look exactly like the poisoning you are trying to treat.
Third, timing. Emesis is a 0 to 2 hour tool. Forcing a cat to vomit at hour 8 adds risk with no benefit, and the toxin has already left the stomach.
Secondary poisoning and the other cat
A cat that eats a poisoned mouse can take in a small dose of anticoagulant. One mouse is usually a low dose, but 2 or 3 mice over a week is a real exposure, and the same 48 and 72 hour PT checks apply.
Separate the cats, pick up every bait station within 20 m of the house, and check sheds, garages and balconies for 5 to 10 stray blocks. Store baits in a locked box at least 1.5 m off the floor, and never place them where a cat can reach through a gap of 5 cm.
Do these 5 things in the next 30 minutes
- Photograph the packaging and bag it; do not rinse the chewed block.
- Weigh the cat, and estimate how many blocks are missing down to 1 block.
- Call the clinic and say the active ingredient, not the brand alone.
- Do not induce vomiting, do not give milk, oil or salt water, and do not wait for symptoms.
- Ask for a baseline PT, calcium and creatinine at hour 6, plus a written recheck at 48 and 72 hours.
Go immediately if the cat is twitching, has pupils of 2 different sizes, breathes over 40 times a minute, or has gums that went from pink to pale in an hour. If the cat ate a plant instead of a bait, the plant list at toxic houseplants emergency and the toxicity checker will name it faster than a phone call. For the day-by-day bleed watch after an anticoagulant, follow the rodenticide timeline.
Frequently asked
How fast do I need to act after my cat eats rat poison?
Within 2 hours if you can, because decontamination works best in that window, and within 6 hours for a baseline blood sample and charcoal. Do not wait for symptoms: anticoagulant baits stay silent for 2 to 5 days, and by the time the gums are pale the cat may need a transfusion.
Can I make my cat vomit with hydrogen peroxide or salt water?
No. Cats tolerate 3 percent peroxide poorly and it irritates the stomach, salt water can push sodium up and cause tremors, and if the bait is a neurotoxin the cat may aspirate vomit into the lungs. Emesis is a clinic decision made with the packaging, the weight and the clock in front of the vet.
The box is gone. Is the brand name enough?
It helps but it is thin. Try to recover the box, the bait station or a photo of the label, because the clinic needs the active ingredient, the concentration in percent, the block weight and how many blocks are missing. Without those 4 numbers the plan has to assume the worst class.