BOAS in Dogs: Breathing Problems in Flat-Faced Breeds

BOAS in dogs, short for brachycephalic obstructive airway syndrome, is a breathing condition in flat-faced dogs where a short skull shape leaves the nose and throat cramped, so air has to squeeze through narrowed airways. (“Brachycephalic” simply means short-headed or flat-faced.) The PDSA links it to selective breeding and describes it as a serious health and welfare issue.

If your dog snorts, snores while awake or struggles on walks, speak to your vet.

At a glance

• What it is: a breathing problem caused by narrowed airways in flat-faced dogs. It tends to get worse over time.
• Who it affects: flat-faced breeds such as Pugs, French Bulldogs and British Bulldogs. Not every flat-faced dog develops it.
• Urgency: soon for noisy breathing. Contact your vet immediately for sudden breathing problems, and treat collapse as an emergency.
• Vet needed? Yes, for assessment and to discuss options such as surgery.

Signs to look for

The PDSA and RSPCA list these:

• Noisy breathing, snorting or snoring, and disturbed sleep
• Difficulty or laboured breathing
• Not wanting to exercise, or tiring quickly, and poor tolerance of heat
• Gagging, retching, regurgitating or vomiting
• Sleeping with the head propped up (RSPCA)
• Blue-tinged skin or gums (cyanosis) and collapse

The UK Brachycephalic Working Group states that noisy breathing in flat-faced dogs at rest or light exercise is never normal. The PDSA says signs can show in puppies but often start between two and four years old, and usually worsen without treatment.

Causes and risk factors

The skull shape is the underlying cause. The PDSA describes four problems that can occur alone or together: narrowed nostrils, too much tissue crammed into the nose and throat, an overlong soft palate (the flap at the back of the roof of the mouth) that partly blocks the airway, and a narrow windpipe. The extra effort of breathing can lead to collapse of the windpipe and voice box, which is harder to treat once it develops.

The PDSA lists Pugs, Pekingese, French Bulldogs, British Bulldogs, Shih Tzus and Boston Terriers as commonly affected. The Dogs Trust’s list of flat-faced breeds is longer and, it says, not exhaustive (it includes Boxers, Cavalier King Charles Spaniels, Chihuahuas and Shar Peis), so the two lists differ. The Dogs Trust adds that any dog can have BOAS, especially crossbreeds with shortened noses. The PDSA says extra weight can make breathing problems worse, so see our page on obesity in dogs.

When to call your vet

Book a vet appointment for any BOAS signs, including noisy breathing. The PDSA says sudden breathing problems need immediate contact with a vet, and that heatstroke or a sudden worsening that leads to collapse is an emergency. If your dog suddenly has trouble breathing, contact your vet immediately. Our guide to finding a vet can help you find a practice, and our page on heatstroke in dogs covers hot-weather risks. Not sure how urgent it is? Our sick dog symptoms guide may help.

How vets diagnose it

The PDSA says diagnosis is usually based on signs and an examination, sometimes with a short walk to see whether exercise brings the signs on. An endoscope (a thin camera) may be used under general anaesthetic, especially if surgery is planned, and specialist referral can involve CT scanning. For Bulldogs, French Bulldogs and Pugs, specially trained vets can also assess the dog through the Kennel Club’s Respiratory Function Grading Scheme, where the vet listens to the dog’s breathing at rest and after three minutes of brisk movement.

What vets generally do about it

The PDSA says BOAS can’t be cured, but surgery can improve breathing and quality of life. Operations can include widening the nostrils, shortening the soft palate and removing small sacs from the voice box. Flat-faced dogs have a higher risk of anaesthetic complications, and surgery cannot remove every effect of BOAS. The Dogs Trust says mild cases are managed with a healthy weight and limited strenuous exercise, with surgery for more severe cases. Your vet will decide what suits your dog, and may refer you to a specialist.

Living with it and prevention

Once your vet has advised, the PDSA, RSPCA and Dogs Trust suggest:

• Keeping your dog slim, as extra weight worsens airway pressure
• Using a harness instead of a collar, building exercise up gradually and letting your dog rest when they struggle
• Walking only in cool parts of the day, keeping walks short and carrying water

On prevention, the PDSA says affected dogs should not be bred from, even after surgery. If you’re thinking of getting a Bulldog, French Bulldog or Pug puppy, it advises checking the parents’ Respiratory Function Grading results, though a low grade doesn’t guarantee a healthy puppy. The PDSA says earlier treatment is likely to have a better outcome, even for mild signs. Surgery can be costly, so see our pet insurance guide.

Related conditions

• Heatstroke
• Tracheal collapse
• Obesity
• Kennel cough and our guide to why dogs cough (other causes of coughing, worth ruling out with your vet)

Browse the full A-Z of dog illnesses and conditions.

Specialist help

The Kennel Club and University of Cambridge run the Respiratory Function Grading Scheme for Bulldogs, French Bulldogs and Pugs. Assessments are done by specially trained vets from 12 months of age, and grades run from 0 (clinically unaffected) to 3 (clinically affected with severe signs). It is aimed at owners, breeders and puppy buyers, so ask your vet about it.

Sources

• PDSA: BOAS, breathing problems in flat-faced dogs
• Dogs Trust: Brachycephalic dogs and BOAS
• RSPCA: How to care for dogs with brachycephaly
• The Kennel Club: Respiratory Function Grading Scheme
• UK Brachycephalic Working Group (hosted by the Royal Veterinary College): Noisy breathing in flat-faced dogs is never normal

This page is general information, not veterinary advice. If you are worried about your dog, speak to your vet. Written by Georgiana & Figo, who are dog owners, not vets. Have a look around Calmshops for everyday dog essentials.