Of all the components of the brachycephalic airway, this is the one you can see with your own eyes before money changes hands.
How to assess it yourself
Look at the puppy's nostrils in good light while it is breathing calmly. Open, rounded nostrils are what you want. Narrow vertical slits are not.
Then watch as it inhales. Healthy nares stay open or flare slightly. Stenotic nares draw inwards and close further under the negative pressure of the breath, which is exactly when the dog needs them open. A puppy whose nostrils close as it breathes in is telling you something no photograph will.
Why correcting it early matters
Alaplasty is among the cheapest and lowest-risk procedures in the whole brachycephalic repertoire, and it is most effective done before secondary changes accumulate. A dog working hard to inhale through pinched nostrils generates strongly negative pressure through the rest of its airway, which over time drags soft tissue inwards — everted saccules, and eventually laryngeal collapse.
Widening the nostrils at eight months costs a fraction of managing the consequences at four years.
Signs to look for
- Nostrils that appear as narrow slits rather than open openings
- Nostril walls collapsing inwards on inhalation
- Noisy breathing, worse when excited
- Mouth breathing at rest
- Reduced exercise tolerance
What causes it
- Selective breeding for a shortened muzzle
- Overly soft nasal cartilage that collapses under inspiratory pressure
- Inherited conformation
How it is diagnosed
Visual, and gradeable by a vet. Watch the nostrils as the dog inhales — if the walls draw inwards and close rather than staying open, the nares are functionally stenotic even if they look adequate at rest.
Treatment options
- Surgical widening — alaplasty or wedge resection
- Often performed at the same time as neutering to avoid a second anaesthetic
- Weight management
- Harness rather than collar
Reducing the risk
- Look at the nostrils before you choose a puppy — this is the one BOAS component you can assess yourself
- Buy from parents graded 0 or 1 under the Respiratory Function Grading Scheme
- Correct early rather than waiting, since chronic effort causes secondary damage
Insurance: Very frequently noted at a puppy's first veterinary examination, which places it before most policies begin. Once 'stenotic nares' appears on the record, the whole BOAS complex is usually excluded. This is the single strongest argument for insuring before that first appointment.
This is screenable. Ask the breeder for Visual assessment, and Respiratory Function Grading of the parents results for both parents before you commit to a puppy. See our full breeder question list.
What we would actually buy
Lifetime cover with per-condition limits that hold up against a single IVDD surgical episode. Compare the per-condition limit rather than the headline annual figure.
Best for:Owners insuring from the day of collection
Check current pricePassive cooling with no power or freezer time. Useful for warm afternoons when the dog cannot be walked, though it is management rather than protection — it will not stop an episode already under way.
Best for:Summer months, and any dog with diagnosed BOAS
Check current priceA collar loads the throat of a dog whose airway is already restricted. A Y-front harness sits across the chest and leaves the trachea clear, which is the single cheapest intervention that meaningfully improves breathing on a walk.
Best for:Every French Bulldog, from the first walk onwards
Check current priceWe earn a commission if you take out a policy through this link. It does not affect what you pay.
As an Amazon Associate we earn from qualifying purchases.
Common questions
Can stenotic nares be fixed?
Yes. Surgical widening of the nostrils is a straightforward, relatively inexpensive procedure with a good outcome, and it is frequently done at the same time as neutering to avoid a second anaesthetic.
How do I know if my French Bulldog has stenotic nares?
Look at the nostrils while the dog breathes in calmly. If they are narrow slits, or if the walls collapse inwards on inhalation rather than staying open, they are stenotic.
Do all French Bulldogs have stenotic nares?
A large proportion do, to varying degrees. It is one of the most common components of brachycephalic airway obstruction, and one of the few you can assess before buying a puppy.
Related reading
This page is general information, not veterinary advice. Every dog is different. If you are worried about your French Bulldog, speak to your vet.