Conjunctivitis is the general umbrella term we use to describe a degree of inflammation of the eye. It’s a generic description of a “red” or inflamed eye which can be associated with a variety of different conditions.
Conjunctivitis in dogs can manifest with a magnitude of signs, even those of a very subtle, barely visible degree of dried or fresh watery discharge around your dog’s eyes. This can be perceived as normal by some owners but can also suggest the very early stages of a problem. Not all cases manifest with profound discharge and irritation!
Aside from the very mild cases, conjunctivitis can manifest with marked purulent discharge around one or, most commonly, both eyes which can cause severe pain, discomfort, irritation and compromise of eyesight and should not be overlooked.
These manifestations suggest that there is a high possibility a more serious underlying problem, which can be vision threatening in some cases, may be underlying.
Cases of conjunctivitis are usually either self limited (due to temporary irritation from grass, dust, water your dog has been swimming in) or resolve within a few days after instigating treatment from your vets.
Any case that persists or deteriorates despite generic treatment, will be benefited from a referral and assessment by an ophthalmology specialist. Please do not use over the counter medication without seeking advice from your vets.
What Is Conjunctivitis in Dogs?
The term conjunctivitis is used to describe inflammation (and not infection) of the conjunctiva and/or eyelids in the form of redness, swelling (“puffiness”) and copious clear or purulent discharge, usually present in both eyes.
The conjunctiva is a thin membrane lining the white part of the eyes (called sclera) and the inner part of the eyelids. The role of the conjunctiva is to act as a protective barrier to injuries and irritating particles, produce part of your dog’s tears and nourishing substances and regulate the immune defences of the surface of the eye.
Conjunctivitis affects almost always both eyes but the severity is not always the same in both eyes. The signs of true primary conjunctivitis are almost always acute while chronic changes usually suggest either an underlying problem which has not been addressed properly or improper course of treatment.
Recurrence of the problem is common and this can be associated with either improper duration of the treatment or, if empirical treatment without a definitive diagnosis has been trialled, persistence of the underlying primary problem will also lead to recurrence.
It is therefore of paramount importance to try to achieve a correct and definitive diagnosis when possible.
Types of Conjunctivitis in Dogs
Conjunctivitis in dogs can be classified and grouped based on the underlying aetiology. The main types of conjunctivitis we see and treat are associated with:
1. Allergies
Allergic conjunctivitis in dogs accounts for the highest proportion of the cases we see. It is associated with irritation caused by either environmental factors, such as pollen, dust, mites, grass etc or by allergens present in foods and diets. This type of conjunctivitis affects almost always both eyes and can be associated with other signs, such as skin irritation and itchiness or ear problems.
2. Infectious agents
Infectious conjunctivitis is less common in dogs but certain bacteria present in the environment or viruses that can be contracted between dogs can lead to a flare up of conjunctivitis.
3. Irritants or foreign bodies
Things that are less likely to cause problems to us, such as laundry detergents, cleaning products, shampoos, battery operated or plug-in scent diffusers and candles can often be irritating for dogs and lead to signs of conjunctivitis.
In addition, we should not forget that dogs, regardless of their size (large, medium or small) are much closer to the ground than us and we do not often appreciate their perspective. This means that they are far more often in contact with long grass, tree branches, grass seeds, soil and materials that can become irritating if it becomes stuck in the eye.
4. Immune-mediated conjunctivitis
A condition associated with improper response of the immune system, leading to the body attacking itself, is a condition that is frequently seen and is associated with other underlying conditions such as dry eye, skin or ear problems.
Common Causes of Conjunctivitis in Dogs
The most common causes of conjunctivitis in dogs, and the highest proportion of cases of primary conjunctivitis, is exposure to environmental allergens and bacteria in the environment. Although a seasonal trend can become apparent, these types of conjunctivitis can flare up any time of the year.
In addition to these, anatomical problems (problems associated with the structure of the eyelids and the face of the dogs) can also lead to conjunctivitis. This occurs due to the presence of aberrant eyelashes (called distichia), inward rolling of the eyelid (a condition called entropion) or exposure of the eyes due to breed-related characteristics in brachycephalic breeds.
Conjunctivitis can occur secondary due to a plethora of serious eye problems and is the most common sign we see associated with pain and discomfort. Serious, vision threatening conditions that can cause conjunctivitis or conjunctivitis-like presentation are corneal ulcers, long-standing and improperly treated dry eye, foreign bodies (like thorn/grass) stuck to the eye(s), glaucoma and uveitis among others.
Symptoms of Conjunctivitis in Dogs
Typical symptoms
The most common presentation and features of almost every case of conjunctivitis is rapid development of redness, usually in both eyes but not always at the same time, squinting of the eye(s) and presence of green or yellow discharge around the eyelids.
In addition, some dogs will try to paw their eyes due to the irritation caused by the underlying problem. These signs can flare up rapidly and are usually encountered after a walk.
Warning signs
Signs that should not be ignored include excessive, severe pain leading to inability to open one or both eyes, changes in the appearance of the surface of the eye (the cornea becoming “clouded”, “white” or “blue” in appearance), severe swelling of one or both eyes, vision compromise or loss of vision and changes in general behaviour (i.e., eating less, less inclined to go for walks etc).
These are signs that can be associated with a much more serious problem, which requires immediate veterinary attention. If the signs of conjunctivitis do not improve significantly within a period of 48 hours following treatment, further investigations should be considered.
How Is Conjunctivitis Diagnosed?
Diagnosis of conjunctivitis is based on the ruling out of other underlying, more serious conditions that can present with similarities to conjunctivitis. An appointment at a vet is required in order to assess the eye for the following:
- Signs of an embedded foreign material, which could be causing irritation and conjunctivitis-like signs, review the tear production and ensure your dog is not suffering from early stages of dry eye
- Measure the pressure of the eye to ensure glaucoma or uveitis are not part of the problem
- Apply a dye, called fluorescein dye, which aims to reveal ulcers and scratches to the surface of the eye (cornea)
Although conjunctivitis is not a condition that threatens the integrity of the eye and vision, misdiagnosis and ignoring more serious conditions, like the ones described above, can lead to irreversible damage to the eye and loss of vision.
Treatment Options for Conjunctivitis in Dogs
Treatment of conjunctivitis relies on treatment of the underlying condition(s), leading to irritation. First of all, it is important to ensure that any factors exacerbating conjunctivitis (as highlighted previously) are addressed or, if possible, removed from your dog’s environment to ensure the condition can be treated adequately without relapses.
Following that, treatment ranges from the use of topical lubricating drops alone to combination of those with topical anti-inflammatory or antibiotic drops, depending on the suspected underlying aetiology of the problem.
Using human eye drops without establishing what is the underlying cause of conjunctivitis can lead to serious complications as certain drops (i.e., steroid anti-inflammatory drops) are contraindicated in cases of underlying corneal ulceration.
When it comes to treatment of conjunctivitis, although rapid improvement and resolution of the clinical signs might be evident within just a few days after the use of the prescribed medication, it is important to follow your vet’s advice and complete the course as instructed. Cessation of medication before the problem is fully controlled and treated, can lead to flare up of a problem.
Can Conjunctivitis in Dogs Heal on Its Own?
In some cases, conjunctivitis in dogs can heal and resolve on its own. This is commonly seen in cases where the irritating factor leading to conjunctivitis is caused by specific types of grass, pollen, swimming in rivers or ponds which can occur during a walk. Gentle wash of the eyes with sterile saline can reduce the load of these irritating factors from the surface of the eyelids and eye and lead to rapid resolution of the problem.
However, the majority of cases will persist for longer than a few hours or a day and they do require veterinary assessment. The reason veterinary assessment in cases of conjunctivitis is important is to first of all establish a targeted plan of action but, of equal importance, to ensure it is just a case of conjunctivitis and no more serious conditions are present.
Delaying treatment can lead to prolonged irritation and discomfort which can in turn lead to self harm if your dog’s eyes are very itchy and they are trying to scratch and rub on surfaces or furniture. Factors such as self harm and corneal ulcer can increase the complication rates and lead to more permanent harm.
When Should You See a Vet Specialist?
The signs of conjunctivitis should improve, in most cases, within a matter of days to a maximum a week. The signs of conjunctivitis should not return shortly after the drops are discontinued (i.e., within a few weeks to a month); this would suggest that your dog might be suffering from more than just a case of conjunctivitis and further investigation is recommended.
In any case that:
- The clinical signs of eye discharge, eye irritation and redness persist despite treatment
- Your dog is showing extreme pain and discomfort and keeping their eye(s) shut most of the time during the day
- They appear subdued, lethargic and not interested in food, treats and walks as usual
- Their vision is altered or affected
You should seek urgent referral to a veterinary ophthalmology specialist to assess if there are complicating factors or conditions that need to be addressed and treated in a more targeted way.
Why Specialist Eye Care Matters
Most vets have the tools and expertise to treat simple cases of conjunctivitis but when it comes to complicated conditions (i.e., small eyelashes irritating the eye, foreign material that requires specialised kit to identify, measurement of parameters like the pressure of the eye and thorough inspection of the front and back chamber of the eye), advanced expertise and equipment is needed to reach a definitive diagnosis.
A veterinary ophthalmologist has the knowledge and expertise to identify and treat in an effective way all conditions affecting an eye and create a tailored plan to your dog’s needs.
In cases where a clear diagnosis has not been reached by your GP vet and the problem persists or worsens despite treatment, you should be considering assessment by a veterinary ophthalmologist. Eye conditions can progress very rapidly and in many cases waiting for as little as a day can lead to irreversible damage to your dog’s eye.
A pet eye specialist has all the required expertise, knowledge and equipment required to provide you with an accurate diagnosis and targeted treatment, which reduces your pets discomfort and your stress, knowing you are doing the best that you can for your dog.
In general, conjunctivitis is a very common condition and, in most cases, an easily treated and resolved condition in many dogs, especially puppies and dogs <2 years of age. As long as your dog’s eyes are continuously improving following the recommended treatment by your GP vets, no significant concerns should be raised. However, if the signs relapse or worsen, you should consider a referral to a veterinary ophthalmologist.
If your dog’s eyes aren’t improving, or the signs keep coming back, it’s time to get a specialist involved. Book an appointment with our veterinary ophthalmology team and get a definitive diagnosis.
Frequently Asked Questions
1. Is conjunctivitis in dogs contagious?
In cases of infectious conjunctivitis, it can be highly contagious via direct contact or contact through sharing beds, toys etc
2. How long does conjunctivitis last in dogs?
Depending on the cause of conjunctivitis, some cases will be self limiting within a few days while others will require treatment for a couple of weeks before the problem is fully resolved
3. Can conjunctivitis cause blindness?
Primary conjunctivitis is extremely unlikely to cause blindness. However, if conjunctivitis is the sign of a more serious underlying problem, it could result in compromise of eyesight
4. Can puppies get conjunctivitis?
Puppies are actually more prone to developing conjunctivitis compared to adult dogs as their immune system is not fully developed!