A cat breathing loudly through its nose during sleep is producing a sound veterinarians call stertor, a harsh snoring noise that happens when air passes through a partially narrowed nasal passage or throat. In many cases, occasional light snoring is harmless, especially if your cat breathes quietly when awake and shows no other symptoms. But loud, consistent nasal breathing, particularly if it’s new, can signal anything from a minor congestion issue to a condition that needs veterinary attention.
A healthy cat at rest breathes about 19 to 21 times per minute while sleeping. You can count your cat’s breaths by watching the chest rise and fall over 30 seconds, then doubling that number. Rates consistently above 30 breaths per minute during sleep are worth investigating further.
Why Some Cats Naturally Snore
Flat-faced breeds like Persians, Exotic Shorthairs, British Shorthairs, and Scottish Folds are built to be noisy breathers. These brachycephalic cats have rounded skulls and drastically shortened noses, but the soft tissue inside the skull doesn’t shrink to match. The result is a crowded nasal cavity with narrowed nostrils and partial obstruction of the throat. For these breeds, some degree of loud nasal breathing during sleep is a lifelong baseline, not a sudden problem.
Overweight cats of any breed are also more likely to snore. Excess fat deposits in the tissues around the throat and neck physically narrow the airway, making each breath audible. If your cat has gained weight recently and the snoring appeared around the same time, that connection is worth noting.
Upper Respiratory Infections
Cats living in multi-cat households, shelters, or catteries are especially prone to viral and bacterial infections of the nose and sinuses. A cat with an active respiratory infection will often have nasal discharge (clear or thick and colored), sneezing, and reduced appetite alongside the noisy breathing. Most acute infections resolve within a couple of weeks.
The more concerning scenario involves feline herpesvirus (FHV-1), which is extremely common and stays in a cat’s body permanently after the initial infection. The virus can reactivate periodically and, over time, destroy the delicate scroll-shaped bones inside the nose called turbinates. This damage is irreversible. Cats with chronic turbinate destruction become permanently “snuffly,” breathing loudly through their nose during sleep and often while awake too. Secondary bacterial infections pile on, causing thick nasal discharge and further inflammation. If your cat had a bad respiratory illness as a kitten and has been a noisy breather ever since, this is a likely explanation.
Polyps and Growths
Nasopharyngeal polyps are non-cancerous inflammatory growths that develop most often in young cats. They originate in the middle ear or ear canal and can extend into the back of the throat, blocking normal airflow and trapping secretions. A cat with a polyp typically produces a loud snoring sound both while sleeping and awake, and may also gag, have nasal discharge, or tilt its head. These polyps can be removed, and most cats improve dramatically afterward.
Cancerous masses in the nasal cavity or throat can produce similar obstruction. These are more common in older cats. Any progressive worsening of noisy breathing in a senior cat, especially with bloody nasal discharge or facial swelling, warrants a prompt veterinary visit.
Foreign Bodies and Irritants
Nasal foreign bodies in cats are more common than most owners realize. The typical culprit is a piece of plant material (a blade of grass, for instance) that gets lodged above the soft palate after the cat coughs or vomits. Signs include sudden sneezing fits, gagging, repeated swallowing attempts, and noisy breathing. If your cat was breathing normally yesterday and is suddenly loud today, a foreign body is a real possibility.
Household irritants can also inflame the nasal passages enough to cause audible breathing. Cigarette smoke, strong cleaning products, scented candles, and essential oil diffusers are common offenders. Dust from cat litter, particularly clay-based varieties, is another source. If the noisy breathing seems to come and go, think about whether it correlates with anything in your cat’s environment.
How to Help at Home
If your cat’s loud breathing seems related to mild congestion, a simple steam session can help loosen things up. Run a hot shower in your bathroom with the door closed and the vent fan off, letting the room fill with steam. Sit with your cat in the steamy bathroom for 10 to 15 minutes, letting the moisture-laden air work on the nasal passages. You can do this once daily or more as needed. Don’t place your cat near the hot water directly; the goal is warm, humid air, not heat exposure.
Keeping your home’s air clean also helps. Avoid smoking indoors, switch to a low-dust litter, and skip the essential oil diffuser in rooms where your cat sleeps. If your cat is overweight, gradually reducing their food intake and increasing play can make a meaningful difference in how loudly they breathe.
Signs That Need Urgent Attention
Loud nasal breathing during sleep sits on a spectrum, and the key is recognizing when it crosses from “quirky snorer” into respiratory distress. The following signs mean your cat is struggling to get enough air and needs veterinary care quickly:
- Open-mouth breathing. Cats are obligate nose breathers. A cat breathing through its mouth is in significant distress.
- Blue or pale gums. This indicates inadequate oxygen and is a true emergency.
- Exaggerated belly or chest movement. If your cat’s abdomen is pumping visibly with each breath, the effort to breathe has become abnormal.
- Inability to settle or rest. A cat that keeps shifting positions, standing with elbows pointed outward and neck stretched forward, is working hard to open its airway.
- Rapid breathing above 30 breaths per minute during sleep. Occasional readings above 30 can happen, but consistently elevated rates suggest a cardiac or respiratory problem.
- Collapse. A cat that collapses while breathing loudly needs emergency care immediately.
What a Vet Visit Looks Like
If you bring your cat in for noisy nasal breathing, your vet will start with a physical exam, listening to the chest, checking the throat, and looking at the ears (since polyps often originate there). Depending on what they find, next steps may include imaging of the skull to look for masses, foreign bodies, or turbinate damage, and possibly a scope examination of the nasal passages and throat while your cat is sedated.
Treatment depends entirely on the cause. A foreign body gets removed. A polyp gets surgically extracted. Chronic rhinosinusitis from herpesvirus damage is managed rather than cured, typically with periodic courses of treatment to control secondary infections when flare-ups occur. For brachycephalic cats with structural narrowing, the focus is usually on weight management and environmental adjustments to minimize additional airway irritation.
The most useful thing you can do before the appointment is track the pattern. Note when the noisy breathing started, whether it happens only during sleep or also when awake, whether it’s getting louder over time, and whether your cat has any other symptoms like discharge, sneezing, or appetite changes. That timeline helps your vet narrow things down quickly.