Symptom · Cats
Cat breathing with mouth open: what it means and when to call the vet
Cats rarely pant. Apart from a brief pant after very hard play or a stressful car journey that stops within a minute or two, open-mouth breathing in a cat is an emergency — often heart failure, asthma or fluid around the lungs.
By Maya HartCommon causes
- Congestive heart failure, often from hypertrophic cardiomyopathy
- Asthma attack
- Fluid or air around the lungs
- Severe anaemia
- Heatstroke
- Trauma, such as a road accident or fall
What you can do at home
- Go to the vet immediately — this is not a wait-and-see sign
- Keep your cat calm and cool; carry them in a carrier
- Don’t restrain or force water
- Phone ahead so the clinic can prepare oxygen
What the vet may do
- Oxygen straight away
- Ultrasound of the chest and heart
- Drain fluid from around the lungs
- Diuretics for heart failure, or bronchodilators for asthma
Prevention
- Regular check-ups — heart murmurs and gallop rhythms can be found early
- Count your cat’s resting breathing rate occasionally
The details
Dogs pant to cool down; cats, for the most part, don’t. A cat who breathes through an open mouth is usually short of oxygen. Heart disease is a common cause, and in cats it is often silent: many cats with hypertrophic cardiomyopathy show no signs at all until they suddenly struggle to breathe.
Counting your cat’s breaths while they sleep is a useful habit. A normal resting rate is usually under 30 breaths a minute. A cat with known heart disease whose sleeping rate rises above 30–40 needs a vet promptly, even if they otherwise seem well.
Questions owners ask
Is cat breathing with mouth open an emergency?
Yes — treat it as an emergency and go to a vet now. Go now if you see: any open-mouth breathing at rest; more than 40 breaths a minute while resting; blue, grey or pale gums; sitting hunched with elbows out and neck stretched; sudden paralysis or pain in the back legs (possible blood clot).
What causes cat breathing with mouth open?
Congestive heart failure, often from hypertrophic cardiomyopathy; Asthma attack; Fluid or air around the lungs; Severe anaemia; Heatstroke; Trauma, such as a road accident or fall.
What can I do at home?
Go to the vet immediately — this is not a wait-and-see sign. Keep your cat calm and cool; carry them in a carrier. Don’t restrain or force water. Phone ahead so the clinic can prepare oxygen.
Sources
Tailwise is for general information and is reviewed by veterinary professionals, but it is not a substitute for advice from your own vet, who knows your pet. How we check facts