Brachycephalic Ocular Syndrome (BOS)
As a vets in Hexham, Stocksfield and Bellingham, we see many brachycephalic breeds, and unfortunately we also see the poor health that can follow these breeds.
Brachycephalic breeds are those with short noses and flat faces. This includes dogs such as; Pugs, French Bulldogs, Shih Tzus, Boston Terriers, English Bulldogs, Cavalier King Charles Spaniels, and Boxers; and Persian and Exotic/British Shorthair cats.
Brachycephalic breeds are predisposed to eye problems and may have several issues concurrently, hence the term ‘brachycephalic ocular syndrome’. Awareness of the common eye problems these pets may develop allows early recognition and prompt intervention, to promote optimal eye health for your pet.
What are the common eye problems that I should look out for in my brachycephalic pet?
Any changes in your pet’s eyes or if one eye suddenly looks different from the other could indicate a problem. Read about some specific symptoms of eye disease in brachycephalic pets below.
Dry eye (also known as keratoconjunctivitis sicca or ‘KCS’) occurs when there is an insufficient and/or a poor-quality tear film, which typically affects both eyes. An optimal tear film is vital for keeping eyes lubricated and healthy.
What causes dry eye?
- Dry eye is most commonly caused by the destruction of lacrimal (tear gland) tissue by the immune system.
- This causes a gradual reduction in tear film production over time, eventually leading to total loss of tear production once the tear gland is completely destroyed.
- Once the tear gland tissue is lost it is unlikely to recover, so prompt recognition of symptoms and treatment is essential.
- Brachycephalic breeds are 3.63x more likely to develop dry eye than non-brachycephalic breeds1.
- Due to their face shape and exposed corneas, brachycephalic breeds also have difficulty maintaining a normal tear film on the surface of the eye which can worsen dry eye.
What are the symptoms?
- In the initial stages, pets with dry eye often experience recurrent bouts of sore, itchy eyes with sticky, grey-yellow or crusty discharge.
- Corneal ulcers and chronic corneal changes, such as pigmentation, may also develop later on and can cause sight loss if left untreated.
- Dry eye can be diagnosed by your veterinary surgeon based on clinical examination and assessment of the tear film using a Schirmer tear test (STT).
- A STT involves placing little strips of paper inside your dog’s lower eyelid and is usually tolerated well by most pets.
What is the treatment?
- Treatment of dry eye includes applying medicated eye drops on a daily basis to prevent the immune system from attacking the tear gland – if caught early enough medication is usually successful at reversing the condition .
- TREATMENT IS LIFELONG! If medicated drops are stopped then the cycle of tear gland destruction will start up again.
- Tear replacement drops are also important to keep the eye lubricated and prevent it from drying out- hyaluronic acid-based lubricants are superior as they lubricate the eye for longer and are generally well tolerated.
- Eye cleaners are often useful to remove the build-up of crust and discharge that is frequently seen in patients with dry eyes- it is important to select an eye cleaner that is safe to use in and around the eye.
- Should you have difficulty applying any of the prescribed medications, please speak to your vet ASAP as they may be able to advise of an alternative solution.
Corneal irritation and ulceration
- Brachycephalic breeds have protruding eyes making them more exposed to the elements, which can lead to dryness, damage and irritation.
- Corneal ulceration (where the surface of the eye is ‘wounded’) is a common resulting complaint in brachycephalic breeds.
- Corneal ulcers are very painful and can rapidly deepen and enlarge (known as ‘melting’), which if not treated promptly can cause blindness in the affected eye.
- Brachycephalic breeds possess an increased risk of corneal melting so need to be treated with even more care and attention (59-65% of dogs with ‘melting’ ulcers are brachycephalic breeds2,3).
- Symptoms of a corneal ulcer include; irritation, blinking/winking, redness, cloudy eye, watery eye or other ocular discharge (green-yellow-grey).
- A corneal ulcer is a medical emergency therefore veterinary advice and treatment must be sought immediately.
Tear overflow and staining
- Due to the flat-face and abnormal eyelid anatomy seen in many brachycephalic breeds, tears may not drain effectively, and therefore may overflow onto the face.
- Tears contain porphyrin pigments that turn brown on the coat, resulting in unsightly ‘tear staining’.
- Tear staining is largely a cosmetic problem and your pet will lead an otherwise normal life, however as it can occur due to an underlying ocular disease (e.g., irritation that causes overproduction of tears) it is important to make sure these have been ruled out by a vet.
The good news is that lots can be done to help improve eye health in brachycephalic pets.
Regular vet examinations
- It is recommended to perform ocular screening examinations at least every 12 months in at-risk breeds (such as brachycephalic pets).
- Screening examinations could coincide with annual health checks performed at booster vaccinations.
- Screening examinations will help to identify any anatomical problems that require surgical intervention, test tear film production (using a Schirmer tear test to identify dry eyes) and look for any active problems/conditions (e.g., ulceration, infection, inflammation).
- For patients that have been diagnosed with an ocular condition (e.g., dry eye), more frequent veterinary examinations will be required.
Keep their eyes clean
- Remove any debris or discharge that builds up around your pet’s eyes (or in the skin folds that sit nearby) to keep them clean and minimise the likelihood of infections developing.
- Performing this as part of your pet’s daily hygiene routine provides an opportunity for you to promptly identify any changes or problems with your pet’s eyes, so that you can alert your vet and seek treatment early on.
- It is important to use a cleaner that is safe to use in and around the eye.
- Regular eye lubrication should be implemented from a young age as part of a brachycephalic pet’s daily routine, to help support eye health.
- This is also a good way to get your pet used to having eye drops instilled, as many brachycephalic pets will, unfortunately, develop eye problems during their lifetime that require the administration of eye medication.
- Lubrication is extremely important if your pet has been diagnosed with dry eyes.
- Your pet’s eyes require additional lubrication if going into hospital for a procedure. Many things about a vet visit can negatively affect tear production (e.g., stress, sedation/anaesthetic drugs, warm kennels) so your vet will ensure eye lubrication is given before, during and after any procedures where this may be a concern.