Anticoagulant rat bait does not make a cat bleed on day 1, and that delay is where most cases go wrong. The bait blocks vitamin K recycling in the liver, factor VII drops by about half every 6 hours, and a cat that is normal at hour 6 can have a nosebleed on day 4. Four checkpoints decide the case: 0, 2, 6 and 24 hours, then a prothrombin time (PT) at 48 hours that must reach 2 times baseline before anyone mentions stopping treatment.
Hour 0: 6 questions before the carrier
Settle 6 facts first: which product (box, bait station or label photo), the concentration in percent, most blocks sit at 0.005, how much is missing in grams, when it was eaten within a 2-hour window, the cat's weight to 0.1 kg, and any liver or bruising history. A 20 g block at 0.005 percent holds 1 mg of active ingredient, so a 3 kg cat chewing half a block is a real exposure even while eating normally.
Do not induce vomiting at home: hydrogen peroxide at 3 percent burns the stomach lining, cats vomit unpredictably, and bait often ends up in the lungs instead of the bowl. Do not buy vitamin K1 from a feed store either. The amount follows the bait type, the exposure and the weight, and it is set after a PT, on prescription.
Hour 2: the stomach is still worth emptying
Vets induce vomiting only when 3 things line up: arrival within 1 to 2 hours, a fully alert cat, and a known product. Past 4 hours the stomach is mostly empty and the attempt only adds aspiration risk. Activated charcoal is a clinic decision, binds what is left, and never replaces the 48-hour PT.
This is also the window for the cheap phone call. Give the product name, the percent, the missing grams, the time and the weight. A clinic converts that to mg in under 1 minute and tells you whether to drive now or at 24 hours.
Hour 6: a normal cat proves nothing
Factor VII has the shortest half-life of the vitamin K dependent factors, about 6 hours. At hour 6 it can still be above 50 percent of normal, enough to clot normally, so a cat that is eating and jumping is expected rather than reassuring. The bait clears from plasma in 2 to 3 days while the liver block runs 4 to 6 weeks, which is why the pills outlast the poison by a month.
What helps at hour 6 is mechanical: photograph the gums, count the resting respiratory rate (30 breaths per minute or fewer), keep the cat indoors with 1 litter box and no stairs. Bruising appears first where fur is thin: inner thigh, gum line, pinna. A new 1 cm bruise is a same-hour call.
Hour 24: the first PT worth acting on
A PT at 24 hours catches fast absorbers while the cat still looks fine. Seen at hour 2: draw at 24 and 48. First contact at hour 24: draw now and repeat at 72. One normal result never closes the file, because second-generation baits such as brodifacoum and bromadiolone can lift the PT between 72 and 96 hours.
| Hours after bait | Factor VII activity, approx | PT vs baseline | Action |
|---|---|---|---|
| 0 | 100 percent | 1.0x | Call the clinic, keep the box |
| 2 | 80 to 90 percent | 1.0 to 1.1x | Clinic may induce vomiting |
| 6 | 50 to 60 percent | 1.1 to 1.2x | Normal behaviour is expected |
| 12 | 25 to 35 percent | 1.2 to 1.5x | Book the 24-hour PT |
| 24 | 6 to 12 percent | 1.5 to 2.5x | Draw PT, start K1 if high |
| 48 | under 5 percent | 2.0 to 4.0x | Treat if 2x or more |
| 72 to 120 | under 5 percent | 3.0 to 5.0x | Bleeding risk peaks |
Read the table as a trend, not a timetable: 5 g of bait and 50 g follow the same curve at different heights, and a cat with liver disease starts lower.
Hour 48: why the number has to double
PT is reported in seconds against a control, so 12 against 10 is a ratio of 1.2 and means little. Most protocols treat 2.0 or higher, or a PT more than 3 seconds above the laboratory limit, as confirmed poisoning. A ratio of 1.3 with no signs earns a repeat at 72 hours rather than 6 weeks of pills. Bring the lab's own reference interval: ratios built on another control, or a 6-hour-old sample, are the 2 commonest false readings.
Vitamin K1 is prescription-only for 3 reasons
The amount depends on bait, exposure and weight across a 4 to 6 week course, and a guess either fails or blinds the next PT. The injectable form is for a bleeding cat and belongs in a clinic. And K1 given before a PT erases the evidence, so the 48-hour test can no longer show whether the liver block is real.
K1 also does nothing for 2 other common baits. Cholecalciferol (vitamin D) raises calcium and damages kidneys within 24 to 72 hours; bromethalin swells the brain within 12 to 48 hours and has no antidote at all. Read the active ingredient before assuming K1.
14 days in a cage, not 14 days of watching
Confinement means a large crate or a 2 by 1 m room, no jumping, no stairs, bedding on the floor and litter within 1 m. A cat at 3 times normal PT can bleed into the chest after a 1 m fall, and that shows up as laboured breathing 6 to 12 hours later. Run the full course, commonly 14 days from the last exposure, until a PT 48 hours after the final pill is normal. Skipping that post-treatment check is how a cat bleeds on day 26.
What to bring, and the 5 red flags
- Pale or white gums, or a gum colour clearly paler than a photo from 6 hours ago.
- Nosebleed, blood in the urine, or black tarry stool: bleeding has already started.
- More than 30 breaths per minute at rest, or a chest that looks wider on 1 side.
- Bruising on the inner thigh, pinna or gum line, 2 or more spots within 24 hours.
- Weakness or collapse after a jump, treated as internal bleeding until proven otherwise.
Bring the box or label photo, the exposure time, the weight and any previous bloodwork. For a plant or household product instead of bait, start at /emergency/toxic-houseplants-emergency/ and check the ingredient at /tools/toxic/. Two seizures in 24 hours is a separate emergency: /emergency/seizure-cluster-emergency/.
Tonight: keep the cat quiet indoors, book the 24-hour PT with the product name in hand, and move the remaining bait into a closed metal bin rather than a shelf at 40 cm.
Frequently asked
My cat ate rat bait 6 hours ago and seems fine. Can I wait until morning?
No. A normal-looking cat at hour 6 is expected, because factor VII can still be above 50 percent of normal while the liver block is already running. Call the clinic now, keep the box, and plan the 24-hour PT; second-generation baits can push the PT up between 72 and 96 hours, so a single normal test at 48 hours does not close the case.
Can I give vitamin K1 at home if the vet is closed?
Do not. The amount depends on the bait type, the exposure and the cat's weight, and the course runs 4 to 6 weeks, so a guessed pill either fails or ruins the next PT reading. K1 also does nothing for cholecalciferol or bromethalin baits. Keep the cat quiet indoors and get a PT as soon as the clinic opens.
How long does the cat have to stay in a cage?
Plan on the full course, commonly 14 days from the last exposure and longer for long-acting baits. Confinement stops a 1 m fall from turning into chest bleeding while the PT is still 3 times normal. Do not release the cat until a PT checked 48 hours after the final pill comes back normal.