BOAS explained: breathing health in French Bulldogs

What BOAS is

Short-muzzled breeds have the same amount of soft tissue as other dogs packed into a shorter skull. When the nostrils are narrow, the soft palate is long and the windpipe is small, air has to squeeze through a tighter passage. That extra effort is what we call BOAS.

BOAS is not all-or-nothing. It ranges from no signs at all to dogs that struggle at rest. It can also worsen with age, weight gain and heat, which is why prevention starts with the parents.

Signs to watch for

• Snoring or snorting when awake and at rest.
• Noisy breathing that gets louder with light exercise or excitement.
• Tiring quickly on walks or needing to stop often.
• Sleeping sitting up or with the chin propped up.
• Gagging, regurgitating or swallowing problems.
• Blue-tinged gums or collapse in severe cases, which is an emergency.

A healthy French Bulldog may make some noise, but it should breathe quietly and comfortably at rest and recover quickly after play.

Nostrils, palate and weight

Stenotic nares, nostrils that are pinched closed, are the easiest part to see. Look at the dog's nose from the front: open, comma-shaped nostrils are what you want.

An elongated soft palate cannot be seen without a veterinary examination but often shows itself through snoring and throat noise. The larynx and windpipe can also be narrow.

Weight matters more than many owners realise. Fat around the neck and chest makes every breath harder, so keeping a French Bulldog lean is one of the best things you can do for its airway. Structure plays a part as well: a very heavy nose rope or extremely short muzzle should always be balanced by open nostrils and a good breathing grade.

How respiratory function grading works

Respiratory function grading was developed at the University of Cambridge and is used by the UK Kennel Club, among others. A trained veterinarian listens to the dog's breathing at rest, then after a three-minute exercise test, usually a brisk trot, and again after a short recovery.

• Grade 0: no signs of airway obstruction.
• Grade 1: mild signs that do not affect exercise tolerance.
• Grade 2: moderate signs. Breeding is generally discouraged without careful consideration.
• Grade 3: severe signs. The dog should not be bred, and a veterinary consultation about treatment is recommended.

Grading schemes and their use in breeding programmes differ between countries and clubs. Ask which scheme was used and see the certificate.

Why it matters for breeding

Breeding from parents graded 0 or 1 with moderate features lowers the risk for the puppies. Puppies cannot be graded reliably themselves, since the test is done on adult dogs, so the parents' results are your best guide.

Ask to see the grading certificate for both parents, with the date and the dog's microchip number. Our testing standard is on the Health page, and our health tests guide covers the DNA side.

Choosing a puppy: what you can see yourself

You do not need to be a vet to spot the basics. On the video call, ask to see both parents breathing at rest and after a few minutes of play. Listen as well as look.

• Open nostrils on the parents and the puppy, seen straight from the front.
• Quiet breathing at rest, with the mouth closed or only slightly open.
• Quick recovery after play, without loud rasping or long pauses to breathe.
• A moderate muzzle rather than the flattest face possible.
• A grading certificate for both parents, dated and with microchip numbers.

If a breeder avoids showing the parents moving, or explains away loud breathing as normal for the breed, take that seriously.

Can BOAS be treated?

Surgery can widen narrow nostrils and shorten an elongated soft palate, and for dogs with moderate to severe BOAS it can make a real difference. It is still surgery under anaesthesia, which carries extra risk in short-muzzled breeds, and it does not change the dog's underlying anatomy.

Prevention through careful breeding, a lean body and sensible exercise is far better than treatment.

Everyday care for easy breathing

• Use a harness, never a collar that presses on the throat.
• Keep your dog lean. You should be able to feel the ribs easily.
• Walk in the cool hours and avoid hard exercise in heat. See our guide to heat.
• Learn your dog's normal breathing sounds so you notice changes early.
• Tell your vet the breed before any sedation or anaesthesia.