Respiratory Functional Grading
What Is Respiratory Functional Grading?
Respiratory Functional Grading (RFG) is an internationally recognised method used to evaluate breathing function in brachycephalic (flat-faced) dogs. The Respiratory Functional Grading Scheme has been validated against studies utilising Whole Body Barometric Plethysmography (WBBP) at the Cambridge University Brachycephalic Research Group, which is the internationally recognised gold standard for assessing respiratory function.
The assessment includes:
- Clinical history
- Observation and physical assessment at rest
- Exercise tolerance test (3-minute trot test)
- Repeat observation and physical assessment following exercise test
Dogs are assigned a grade from 0 to 3 according to the severity of their airway compromise.
RFG is currently validated for French Bulldogs, Pugs and English Bulldogs. While RFG can also be assessed in brachycephalic breeds other than those listed above, the grading scheme is limited until validation occurs in these breeds.
While RFG is primarily designed as a tool to evaluate suitable dogs to be used in breeding programs to minimise the severity of brachycephalic disease in future generations, it is also a helpful tool to assess the degree to which non-breeding dogs are affected.
Why Is Respiratory Functional Grading Important?
Respiratory difficulties in flat-faced breeds are often considered ‘normal’, but noisy breathing, exercise intolerance, overheating, and sleep disturbances may indicate significant airway disease.
For Owners
Early identification can:
- Improve quality of life
- Reduce heat intolerance
- Prevent progression of disease
- Help determine whether surgery may be beneficial
- Assist with breeding decisions
For Referring Veterinarians
RFG provides:
- A standardized assessment of BOAS severity
- Objective documentation of clinical status
- Guidance regarding advanced airway investigation
- Information for surgical planning
- Breeding recommendations based on internationally accepted protocols
Which Dogs Should Be Assessed?
Owners may consider testing if their dog:
- Snores heavily
- Pants excessively
- Has noisy breathing
- Tires quickly during exercise
- Cannot tolerate warm weather
- Sleeps in unusual positions
- Experiences episodes of cyanosis or collapse
- Is intended for breeding
Veterinarians may refer dogs:
- Prior to airway surgery
- Following previous BOAS surgery
- For breeding certification
- To objectively assess clinical severity
- When upper airway disease is suspected
How Is the Assessment Performed?
Assessment is completed in four stages:
Step 1: Clinical History
We discuss:
- Exercise tolerance
- Heat sensitivity
- Sleep quality
- Respiratory noises
- Previous airway procedures
Step 2: Resting Examination
Breathing pattern and respiratory sounds are evaluated before exercise.
Step 3: Exercise Challenge
Dogs undertake a controlled period of exercise under supervision.
Step 4: Post-Exercise Assessment
Changes in breathing effort and respiratory noise are assessed and used to assign a grade.
Understanding the Grades
| Grade | Interpretation | Clinical Significance |
|---|---|---|
| Grade 0 | Clinically unaffected | Normal breathing function |
| Grade 1 | Mild signs | Functionally unaffected; breeding may be acceptable |
| Grade 2 | Moderate compromise | Clinically affected; further investigation or treatment recommended |
| Grade 3 | Severe compromise | Marked airway disease requiring intervention |
(Individual recommendations are tailored to each patient.)
Frequently Asked Questions
Is the test painful?
No. Respiratory Functional Grading is non-invasive and does not require sedation or anaesthesia.
How long does the appointment take?
Approximately 30–45 minutes, which includes consultation and functional testing.
At what age should dogs be assessed?
Most dogs are assessed after 12 months of age, although earlier evaluation may be recommended in symptomatic patients.
Does my dog need surgery if they have a high grade?
Not necessarily, but the results will help our surgeons guide recommendations for your dog. The grading system helps determine the severity of disease and whether additional investigations or treatment would be beneficial.
My dog received a high grade (Grade 3). Can I still use them for breeding?
The goal of the RFG scheme is to help improve the health of brachycephalics, first and foremost. Responsible breeding of only minimally affected dogs will improve the health of these dogs in future generations. For validated breeds (French Bulldogs, Pugs and British Bulldogs), it is not recommended to breed from any dogs with a score of 3.
As a breeder, can I choose to publish my dogs results on National Websites like Dogs Australia, to promote my participation in the RFG Scheme?
Yes, any dogs undergoing RFG testing for breeding purposes will have their results recorded on Orchid (an initiative of Dogs Australia for breed specific grading schemes). While the results must be added to the database, you can elect to make them public or private.
Who can perform RFG testing?
Only accredited assessors can perform RFG testing. At QVS we have three surgeons who are accredited assessors – Dr Alecia Evans, Dr David Burgess and Dr Guy Bird. Testing is available at both our Stafford and North Lakes hospitals.
Dr Alecia Evans
Specialist - Surgery
BSc (Hons) BVSc (Hons) GradDipEd MVetClinStud MVetSurg DipECVS
If you have concerns for your pet in connection to this condition we recommend discussing it with your primary care vet in the first instance, or get in touch with our team for more information.
If you need urgent medical help, contact our 24 hour Pet Emergency team at Stafford, North Lakes, or Sunshine Coast on 1300 QLD VET (1300 753 838)