A cat with air trapped around its lung does not cough and does not wheeze. It sits with its elbows out, neck low, and breathes 40 or more times a minute while doing nothing at all. Pneumothorax is one of the few feline emergencies where a clock, not a drug, decides the outcome: a resting rate above 60 or any open-mouth breathing means the cat needs a clinic within 2 hours, and a chest that is tapped in time often walks out the same day.
Three causes, and how fast each one leaks
1. Trauma. A fall from the 3rd floor or higher, a car strike, or a dog bite that punctures the chest wall opens a path for air. Chest injury is common after a road accident, and air can keep entering for 6 to 12 hours afterward, so a cat that looks steady at hour 1 can be gasping at hour 8. Any cat that has fallen 2 floors or more needs a chest film within 24 hours even if it seems normal.
2. Spontaneous rupture. A bulla on the lung surface pops with no accident at all. Siamese and Oriental shorthairs carry a higher risk, and the typical patient is young to middle-aged and was resting quietly 10 minutes before. These cats often leak slowly for 2 to 3 days, with a rate that creeps from 32 to 44 to 56.
3. Iatrogenic. A needle used for thoracocentesis, a jugular blood draw, or a lung biopsy lets air in. Signs usually appear 30 to 120 minutes after the procedure, which is exactly why a cat is watched for 2 hours afterward and why an owner should not drive home in the first 30 minutes.
A 4th pattern kills fastest and deserves its own name: tension pneumothorax. Air enters on every breath and cannot leave, so pressure builds against both lungs and the vena cava. A cat can go from rate 40 to collapse in under 60 minutes, and this is the one case where a vet taps the chest before the x-ray is developed.
The 2-hour line, written as a rule
Count the resting respiratory rate for 30 seconds while the cat sleeps, multiply by 2, and write the number with the time. If the result is over 60, if the cat is breathing with its mouth open, or if the gums look gray or blue, leave for the clinic now and call from the car. If the count sits between 40 and 60, the cat has 2 hours, not 2 days. Between 30 and 40 with normal effort, book a visit within 24 hours. Under 30 with a relaxed posture, photograph the trend for 3 days and keep the routine appointment.
Never try to remove air at home. A needle placed one intercostal space too far forward can cut a lung lobe or a coronary vessel, and the chest wall of a 4 kg cat is roughly 1 cm thick at the tap site. A tap belongs to a clinic with oxygen, suction, and imaging 2 m away.
Four rate bands and what each one means
The table converts a number you can measure at home into an action with a deadline. Bands are for a cat at complete rest, awake but still, and not recently stressed by a carrier or a visitor.
| Resting rate per minute | What you see | Action | Deadline |
|---|---|---|---|
| Under 30 | sleeping, steady flank, no effort | log twice a day, keep film appointment | 3 days |
| 30 to 40 | slight abdominal push, still eating | call the clinic, count every 4 hours | 24 hours |
| 40 to 60 | elbows out, neck low, refuses food | drive in, no food, no carrier fight | 2 hours |
| Over 60 or open mouth | pale gums, gasping, sitting hunched | emergency, oxygen before any x-ray | now |
What happens in the first 30 minutes at the clinic
Oxygen goes on before anything else, usually in a cage with a fraction of inspired oxygen of 0.4 to 0.6, and the cat is handled with the least restraint possible because a struggle can drop a marginal cat. Imaging is a 3-view chest series or a point-of-care ultrasound in under 10 minutes. The tap itself uses a 20 to 22 gauge butterfly or a 3-way tap, and most vets stop at 30 mL/kg per side per pass to avoid re-expansion edema, which can appear 12 to 24 hours after a fast drain of a collapsed lung.
Blood work is not an emergency step but it changes the plan: a packed cell volume below 0.20 L/L, a glucose below 60 mg/dL, or a lactate above 5 mmol/L means the cat is not just breathing badly, it is shutting down.
Tube, surgery, or a watch
A cat that re-accumulates air within 6 hours gets a chest tube, kept 2 to 5 days on suction of 10 to 15 cmH2O. A leak that persists past 5 days, or a CT that shows a ruptured bulla, points to surgery, usually a lung lobectomy, at 1,800 to 5,000 USD. Cats with a single slow leak and no trauma history sometimes resolve in 3 to 7 days with rest and 2 repeat taps, and many vets will try that before cutting.
First 72 hours at home
- Count the rate 3 times a day for the first 3 days, at the same 3 times, and keep the numbers on paper.
- Feed 4 small meals instead of 2, because a full stomach pushes on a healing chest wall.
- No stairs, no jumping to a 1.5 m shelf, no rough play for 10 days.
- Weigh the cat daily; a drop of 100 g in 48 hours means it is working too hard to breathe.
- Keep the carrier out and open, so the next trip takes 2 minutes and not 20.
When to turn the car around and go back
Recurrence after a tap is the rule rather than the exception, and it usually shows up in the first 48 hours. Go back if the resting rate climbs 10 breaths above the discharge number, if the cat hides in a litter box, if the gum color shifts from pink to gray, or if it stops eating for 2 meals. A cat that has had one episode also needs the underlying cause named: a chest film at 4 weeks and a repeat ultrasound at 12 weeks is the usual follow-up, and a heart workup if the first film showed an enlarged left atrium. For the bill, the cost breakdown keeps the emergency fee, the imaging, and the 3-day stay as 3 separate lines instead of one scary total, and if the cat is also straining in the litter box, read the six signs of a blocked cat, because that emergency runs on the same 2-hour clock.
Frequently asked
Can a cat survive pneumothorax without surgery?
Yes. Many cats with a single slow leak and no trauma history resolve with cage rest, oxygen, and 1 or 2 chest taps over 3 to 7 days. Surgery is reserved for a leak that keeps refilling within 6 hours, a leak that lasts past 5 days, or a CT that shows a ruptured bulla. Many traumatic cases need only a tube and time.
How do I count a resting respiratory rate correctly?
Watch the cat while it sleeps or lies still, count each chest or flank rise for 30 seconds, then double it. Do not count while the cat is purring, grooming, or watching a bird, because all 3 push the rate up by 10 to 20. Write the number and the time down, since a trend over 3 days is more useful than one high reading.
Is a 45 breath per minute rate an emergency at 2 am?
A rate between 40 and 60 at rest is a 2-hour problem, including at 2 am, so call the emergency line and go. Above 60, or any open-mouth breathing, is immediate. Do not wait for morning, and do not offer food before the drive in case sedation or a procedure is needed.