Angel, the cat behind Halo, has been counted in her sleep more times than she'd like. Angel's cardiologist asks about it at every appointment, because a cat's sleeping breathing rate is one of the simplest and most useful numbers you can bring to a vet. So it's worth knowing what's normal and what isn't.
First, what's normal while asleep?
A healthy cat who is calmly resting or asleep usually takes somewhere between 15 and 30 breaths a minute. Vet guidance for pets with heart disease uses 30 breaths a minute as the line to watch: a settled, sleeping cat who is consistently above it is worth mentioning to your vet.
Two things can make the number look scarier than it is. Cats breathe faster for a short while when they're dreaming, and they breathe faster when they're warm, have just eaten, or have just played. That's why a single quick look tells you very little.
Common, harmless reasons for fast breathing in sleep
- Dreaming. Fast, shallow breathing with twitching whiskers or paws is usually REM sleep. It passes within a minute or two.
- Warmth. A cat curled up in a sunny spot or next to a radiator will breathe faster.
- Just after activity or a meal. Give it 10 to 15 minutes to settle before you count.
- Purring. A purring cat is harder to count accurately, so wait until it stops.
Reasons to take it seriously
A sleeping breathing rate that stays high across several counts, at different times of day, isn't explained by dreaming or warmth. In cats with heart disease, a rising rate can mean fluid is building up in or around the lungs, which is why vets ask owners to track it. Other conditions, such as asthma, lung disease or an infection, can raise it too.
The pattern matters more than any single reading. A number that creeps up over days or weeks is the thing to catch.
How to count it properly
- Wait until your cat is properly asleep or completely relaxed, not just lying still with their eyes open.
- Watch the flank, the soft area just behind the ribs. One full rise and fall is one breath.
- Count for 15 seconds with a timer, then multiply by four.
- Do it a few times over a few days, at roughly the same time, and write the numbers down.
We go through the full method, and what the numbers mean, in How to Count Your Cat's Resting Breathing Rate.
When to call the vet straight away
- Open-mouth breathing, or breathing that looks like hard work
- A sleeping rate well above 40
- Pale, grey or bluish gums
- Your cat sits hunched with their elbows out, or won't lie down to rest
- A sudden, sharp change from what's normal for them
If any of those sound familiar, don't wait to see if it settles. Call your vet or an emergency vet now.
Making it easy to keep track
The counting is the easy part. The hard part is remembering to do it, and having the numbers to hand six months later. Halo has a built-in 15-second counter, so you tap once per breath instead of watching a clock, and every reading is saved and charted for you. When the vet asks, it takes one tap to show weeks of readings instead of guessing.