A cat pulled from a smoke-filled room can look normal for 30 minutes and be in respiratory failure at hour 6. Carbon monoxide binds hemoglobin 200–250 times more tightly than oxygen, so the blood carries gas but cannot carry air, and the gums may still look pink. Get the cat out, get 100 % oxygen started inside 20 minutes, and plan on 12 hours of observation even if it is walking and meowing. Burns on the coat are the least urgent problem in the first hour.
Why smoke is a blood poison before it is a burn
Smoke from a sofa fire delivers three injuries at once: carbon monoxide that blocks hemoglobin, cyanide and aldehydes that stop cells using oxygen, and soot particles under 2.5 µm that reach the alveoli and inflame them over the next 12–72 hours. Cats are obligate nasal breathers with a narrow larynx, so 1–2 mm of airway swelling is enough to double breathing effort. Carbon monoxide has no smell, and a sleeping cat in a closed room can reach 30 % carboxyhemoglobin before it wakes. That is why a cat found unconscious with no burns is a carbon monoxide case until a blood test says otherwise.
On-scene handling: out, oxygen, 20 minutes
Do not go back into a burning room for the cat. Open windows and doors from outside, cut the power, and let firefighters bring it out: cats hide 1–2 m from where you last saw them, and 30 seconds of 200 °C smoke can drop a person. Once the cat is out, move it to fresh air 10 m upwind, check breathing for 10 seconds, and wipe soot from the nose and mouth with damp gauze. Do not pour water into the nostrils. Start oxygen as soon as a cylinder or clinic is reachable: flow-by at 2–3 L/min or a cage at 40–60 % oxygen. For skin burns, cool with 20–25 °C water for 10–20 minutes, never ice. If burning houseplants were in the room, check our toxic plants guide. Our toxin lookup tool covers the swallowed-poison side of a house fire, such as melted plastic, fire gel and bait.
Cherry-red gums and the lying pulse oximeter
Cherry-red mucous membranes are the textbook sign of carbon monoxide and a poor screening test: they appear in a minority of cases and often only when the level is already high. The pulse oximeter is worse. It cannot tell carboxyhemoglobin from oxyhemoglobin, so it happily reads 96–99 % while a third of the hemoglobin is blocked. Only a co-oximeter blood test gives carboxyhemoglobin as a percentage. In cats, under 5 % is consistent with ordinary exposure, 20–25 % fits moderate poisoning, and readings above 40 % come with collapse or seizures. Do not let a normal oximeter reading talk you out of treatment.
When to drive: minute-level thresholds
Call while you are still outside and give the numbers: cat out at 21:40, breathing 56 per minute, soot on the muzzle, one episode of vomiting. Any cat exposed to smoke for more than 2 minutes goes to a clinic within 2 hours, even if it looks fine, because delayed lung injury peaks at 12–72 hours. Go immediately if the resting breathing rate passes 40 per minute, the gums are grey or blue, the meow is hoarse or silent, there is a cough that produces black spit, the cat is ataxic, or it has had a seizure. A temperature under 37.5 °C or above 40 °C on arrival means shock or heat injury. Kittens under 12 weeks, cats over 10 years and cats with asthma or heart disease decompensate 2–3 times faster, so their threshold drops to any exposure at all.
Carboxyhemoglobin and the 12-hour watch
Ask for carboxyhemoglobin by name, and ask for it before oxygen has been running for 4 hours, because a normal result after long oxygen therapy proves nothing. On room air the half-life of carboxyhemoglobin is 4–6 hours; on 100 % oxygen it falls to 60–90 minutes, and hyperbaric oxygen at 2–3 atmospheres brings it to 20–30 minutes. That is the whole argument for oxygen first, testing second. The 12-hour observation exists because pulmonary edema and airway swelling develop after the cat is home and quiet; most vets re-check at 2, 6 and 12 hours with breathing rate, gum colour and chest auscultation. A cat that is normal at hour 12 with a normal breathing rate can go home with instructions to return if the rate climbs 10 breaths above its baseline.
| Hour | Carboxyhemoglobin (%) | Breathing rate target | Action |
|---|---|---|---|
| 0–1 | over 20 needs oxygen now | under 40 per min | 100 % oxygen, co-oximetry before 4 h of therapy |
| 2 | recheck if over 25 | under 40 per min | Gum colour, auscultation, temperature 38.1–39.2 °C |
| 6 | under 5 expected | under 35 per min | Watch for cough, hoarse meow, rising effort |
| 12 | under 3 expected | under 32 per min | Discharge only if stable for 6 h |
| 24–72 | not needed unless worse | baseline plus 10 | Delayed edema window: any rise means return |
What to carry and how to keep it warm
Take the carrier, 4 sterile gauze pads, a thermos of 20–25 °C water, a digital thermometer and a phone with the fire department's number on speaker. Do not wrap the chest with a tight blanket: a cat with airway swelling needs the chest free to move, and a band around the ribs at 40 breaths per minute costs real tidal volume. Keep the car at 22–24 °C and the windows cracked, since a cat that has inhaled hot gas loses heat fast and arrives at 36.5 °C. Cover the carrier with a dry towel, not plastic, so carbon monoxide off-gassing from the coat can escape. Do not sedate, do not give a human inhaler, and do not offer food or water: a dyspneic cat that aspirates 20 mL adds pneumonia to the smoke injury.
First 72 hours at home
Count the resting breathing rate twice a day for 3 days, asleep or lying still, and write it down: normal is 20–30 per minute, and a rise of 10 or more over baseline is the earliest sign of lung injury. Expect a cough for 3–7 days and a hoarse meow for 2–5 days. Return the same day for laboured breathing, blue or grey gums, refusal to eat for 24 hours, or a temperature over 39.5 °C. Cats with smoke exposure also stop grooming and hide, which is normal for 24–48 hours but not for 72. Skin burns need a recheck at 48 hours even when they look small, because cat burns deepen over the first 2 days.
Executable checklist
- Never re-enter; open from outside and let firefighters retrieve the cat.
- Fresh air, then 100 % oxygen within 20 minutes, flow-by 2–3 L/min.
- Ignore cherry-red gums and the pulse oximeter; ask for carboxyhemoglobin.
- Clinic within 2 hours for any exposure over 2 minutes; 12-hour observation minimum.
- Count breathing at 2, 6 and 12 hours, then twice daily for 72 hours.
Terms mentioned in this article
Frequently asked
My cat seems fine after the fire. Do I still need a vet tonight?
Yes, if the cat was in smoke for more than 2 minutes. Carbon monoxide and soot injury are silent at the start, and lung swelling usually peaks between 12 and 72 hours. A normal examination at hour 1 does not rule that out. Most vets keep the cat for 12 hours of observation with breathing counts at 2, 6 and 12 hours, and a carboxyhemoglobin test taken before 4 hours of oxygen therapy.
Can I use a human pulse oximeter to check my cat?
It will mislead you. A standard pulse oximeter cannot distinguish carboxyhemoglobin from oxyhemoglobin, so it can read 96 to 99 % while a third of the haemoglobin is blocked by carbon monoxide. Only a co-oximeter blood test reports carboxyhemoglobin as a percentage, with under 5 % considered ordinary exposure and above 20 to 25 % moderate poisoning. Judge by breathing rate, gum colour and behaviour instead.
How long does carbon monoxide stay in a cat's blood?
The half-life is 4 to 6 hours breathing room air, 60 to 90 minutes on 100 % oxygen, and 20 to 30 minutes with hyperbaric oxygen at 2 to 3 atmospheres. That is why oxygen comes before testing and why a blood test drawn after 4 hours of therapy can look falsely normal. A cat with a reading above 20 % usually stays on oxygen until the level is under 5 % and breathing is under 35 per minute.