A snakebite on a cat shows up as swelling within 30 minutes, not as a dramatic collapse. Two fangs 8 to 15 mm apart leave 2 small punctures that bleed a little, and the paw or the muzzle swells from 10 minutes onward. The plan is 6 refusals and 3 actions: no cut, no suction, no ice, no tight band, no aspirin, no waiting at home; splint the limb, keep it 10 to 15 cm below heart level, and get to a vet who stocks antivenom.
What the first 30 minutes look like
Most bites land on a front paw, muzzle or nose. Look for 2 punctures 8 to 15 mm apart, a drop of blood that keeps oozing for 5 to 10 minutes, and swelling that starts at the toes and climbs past the wrist within 30 minutes. The skin over the bite goes from pink to purple in 1 to 2 hours.
A bite on the face is the emergency inside the emergency. The muzzle can swell 1 cm in 20 minutes, and the airway narrows with it, so a cat with a nose bite that starts breathing through the mouth at 30 minutes needs a vet in 15 minutes, not 2 hours. Chinese pit vipers such as the mamushi and the green tree viper give exactly this picture: heavy local swelling plus a clotting problem. Elapids such as the many-banded krait are the opposite and far more dangerous — almost no swelling, then weakness and drooping eyelids at 1 to 3 hours.
6 things not to do
- No cut over the fangs: it adds a wound that will not clot, because venom already thins the blood.
- No suction by mouth or by device: venom is absorbed through the mouth lining, and a suction cup pulls out 1 to 2 percent at best.
- No ice or cold pack: cold narrows the skin vessels and turns a 2 cm wound into a 5 cm area of dead tissue.
- No tight tourniquet: a band at arterial pressure for 30 minutes can cost the limb.
- No aspirin, ibuprofen or other NSAID: they add bleeding on top of venom.
- No walking: a cat that walks 50 m spreads venom faster through the lymph channels.
Immobilize below heart level
Splint the leg straight with a rolled magazine, a 30 cm strip of cardboard or a ruler, and 2 bandages 5 cm wide: one above the elbow or knee, one below it, snug enough to hold the splint and loose enough to slide 1 finger under. Then keep the limb 10 to 15 cm below the heart, which means the cat lies flat in the carrier with the bitten leg toward the floor, not held up in your arms. Gravity is the cheapest way to slow lymphatic spread.
Carry the carrier level; no laps, no leash walking, no 20 minute search for the snake. Photograph a dead snake from 2 m away and never bag a live one: a 60 cm viper reaches 30 cm when it strikes.
Observation window: 2 hours, then 12, then 24
| Time from bite | What to check | Danger sign | Action |
|---|---|---|---|
| 0 to 30 minutes | Swelling edge, 2 fang marks | Swelling past the wrist in 30 minutes | Go now, splint on |
| 30 to 120 minutes | Limb girth, gum color, breathing | Gums oozing, 40 plus breaths | Antivenom decision at 2 hours |
| 2 to 6 hours | Clotting test, urine color | Blood that will not clot at 20 minutes | Antivenom, fluids |
| 6 to 12 hours | Weakness, pupil size, swallowing | Drooping eyelids, unable to stand | Ventilatory support |
| 12 to 24 hours | Kidney values, wound color | No urine for 8 hours, black skin | Surgery review at 3 to 7 days |
The 2 hour mark is the first real decision point. A cat with swelling that has stopped at the wrist, normal gums and a normal clotting test at 2 hours is not finished: clotting problems after a viper bite can appear at 6 to 24 hours, and kidney injury shows up at 24 to 72 hours. That is why discharge instructions say to recheck at 12 and 24 hours even when the cat is eating at hour 3.
The bedside clotting test that matters
Take 2 mL of blood into a plain glass tube, leave it at room temperature, and tilt it every 5 minutes. Normal cat blood clots in 5 to 10 minutes; if it is still liquid at 20 minutes, the venom has consumed the clotting factors and antivenom is needed now. Vets call this the 20 minute whole blood clotting test, and it is cheaper than a full panel. A full panel adds PT, aPTT, fibrinogen and platelet count at 0, 6, 12 and 24 hours.
Antivenom is a vet decision, not a syringe you buy
Antivenom is matched to the snake, not to the cat: a viper antivenom does nothing for a krait, and the wrong product still carries the same reaction risk. The usual starting dose is 1 to 2 vials diluted in saline and given over 30 to 60 minutes, with epinephrine drawn up at the bedside, because a reaction can start at minute 5. Antivenom does not repair dead tissue, so a swollen paw may still slough at day 3 to 7 and need surgery; it stops the bleeding and the spread.
Do not give antihistamines, steroids or painkillers before the vet sees the cat. Steroids do not neutralise venom, and NSAIDs make the bleeding worse. If the cat is in pain, the clinic will use an opioid at 0.01 to 0.02 mg per kg, which does not touch clotting.
After 24 hours: the second wave
Swelling peaks at 24 to 48 hours, then either softens or turns black over 3 to 7 days. Kidney values and urine output are the numbers to watch from 24 to 72 hours, because viper venom damages the tubules quietly. A cat that stops eating at day 2 may have dead skin on the paw or a rising creatinine. Wound care after a bite follows the same rules as any puncture, covered in the first hour of a cat bite wound, and an abscess that forms under the dead skin is handled as in cat bite abscess care. If you are unsure whether the snake was venomous, the poison and toxic plant checker lists the common species by region.
5 steps in the first hour
- 1. Splint the leg, 2 bandages, 1 finger of slack.
- 2. Keep the limb 10 to 15 cm below the heart, cat flat in the carrier.
- 3. Call ahead and ask whether the clinic stocks viper antivenom.
- 4. Note the time of the bite, the swelling edge and the snake's color.
- 5. Book the 2, 12 and 24 hour rechecks before you leave.
Terms mentioned in this article
Frequently asked
Should I cut the bite and suck out the venom?
No. Cutting adds a wound that will not clot because venom already interferes with clotting, and suction by mouth exposes you to venom through the mouth lining while removing only 1 to 2 percent of what was injected. Splint the limb, keep it 10 to 15 cm below heart level, and drive to a clinic that stocks antivenom.
The swelling stopped after an hour. Can the cat stay home?
No, because local swelling is only the first phase. Clotting problems after a viper bite often appear at 6 to 24 hours, and kidney injury shows at 24 to 72 hours, both while the cat looks comfortable. Plan rechecks at 2, 12 and 24 hours, with a bedside clotting test and kidney values, and return sooner for drooping eyelids, weakness or no urine for 8 hours.
How is antivenom given, and can I buy it myself?
It is given by a vet as 1 to 2 vials diluted in saline over 30 to 60 minutes, with epinephrine ready at the bedside because a reaction can start within 5 minutes. It is matched to the snake species, so the wrong product does nothing and still carries risk. Never inject antivenom at home; the dose, the dilution and the reaction plan all need a clinic.