Conjunctivitis in dogs

Written by Dr Andrew Miller MRCVSDr Andrew Miller MRCVS is an expert veterinary working in the field for over 10 years after graduating from Bristol University. Andy fact checks and writes for Pure Pet Food while also working as a full time veterinarian. Pure Pet FoodPure Pet Food are the experts in healthy dog food and healthy dogs featured in media outlets such as BBC, Good Housekeeping and The Telegraph. Working with high profile veterinary professionals and nutritionists, Pure Pet Food are changing dog food for the better. - Our editorial process

Conjunctivitis is a pesky but common eye infection that our dogs experience just like us humans do, and we’re sure most people will know just how annoying it can be!

Also known as ‘pink eye’, conjunctivitis occurs when the conjunctiva of the eye becomes inflamed and infected. The conjunctiva covers the globe of the eye, working to prevent infections and block foreign bodies from entering the eye. Strangely, dogs actually have a third eyelid which is also protected by the conjunctiva.

Clearly, the conjunctiva plays a fundamental role in maintaining your dog’s eye health and it’s the thing that we should look for to spot infections. In a healthy eye, the conjunctiva shouldn’t be visible to us, so if you notice it looking red and sore, that’s the biggest indicator of conjunctivitis.

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Many things can cause conjunctivitis, with most of them being minor and likely to happen to every pooch at some point in their life. However, conjunctivitis can sometimes be a symptom of another problem. Possible things the infection can be triggered by are:

  • Foreign bodies caught in the eye such as grit

  • Allergies

  • Injury

  • Bites in the eye area

  • Dry eye (caused by lack of tears)

  • Eye diseases (such as glaucoma)

  • Bacterial infection

  • Viral infection (canine distemper virus, canine herpesvirus)

  • Parasites

  • Tumours

Conjunctivitis caused by issues such as allergies or foreign objects stuck in the eye are classed as non-infectious forms of conjunctivitis, whereas bacterial infections and viral infections are classed as infectious forms.


Usually, the signs of conjunctivitis are pretty noticeable and obvious for dog paw-rents to spot, making it easier to be quick and efficient in getting the right treatment. Look out for these signs:

  • Clear or green discharge from the eye

  • Red eyes

  • Swollen around eye

  • Trying to paw and scratch at the eyes

  • Squinting

  • Blinking more frequently than normal

  • Closed eyes

  • Cloudy eyes

  • Puffy eyelids

  • Crustiness

Conjunctivitis typically starts in one eye and often spreads to the other eye too. Sometimes, if the cause of conjunctivitis is through allergies or a virus, both eyes can be impacted from the very beginning.


If you have had conjunctivitis yourself before, you will know how annoying and irritating it can be. That discomfort will be the exact same for your poor pooch.

If you spot any of the signs detailed above, you must consult your vet straight away so they can determine what type of conjunctivitis it is, as dif-fur-ent types of conjunctivitis require varied treatments.

Non-infectious conjunctivitis is a minor condition and is nothing to worry about, however, it will not clear up on its own. Even if your dog has incredibly mild symptoms of conjunctivitis, you must still seek medical advice immediately to prevent any paw-sible permanent damage.


As stated, the type of conjunctivitis needs to be determined before any treatment can take place, which will occur through an ophthalmic examination.

This entails a thorough analysis of the entire eye structure (eyelids, third eyelid, tear ducts, eyelashes), alongside tear production tests and corneal tests to ensure every section of the eye is working as it should be.

Once completed, the vet will be able to determine what the cause of the infection is and the best method of treatment for it, whether the cause is an underlying disease, eye damage, allergies and so on.


As stated, there are various triggers of the condition, and the treatment methods will vary from case to case.


Everyone knows how annoying it is when something is caught in your eye, and foreign objects get stuck in our pooches’ eyes all the time, as they constantly have their faces hanging out of the window, stuck in the dirt and we dread to think where else!

To remove a foreign object, the vet will usually sedate your pup to remove whatever is causing them irritation. For aftercare, eyedrops/antibiotics will typically be prescribed.


  • Read the instructions and make sure your hands are clean

  • Get your pooch into a position where they can be kept still (maybe enlist a friend to help)

  • Lift your dogs chin upwards with your hand and carefully pull the eyelid down using your thumb

  • Resting your other hand on the top of your dogs head, squeeze the eyedrops into the eye


A very common cause of conjunctivitis is allergies, which are fortunately easily treated. Your vet will most likely prescribe antihistamines that will reduce the inflammation of the conjunctiva. Dogs that suffer with allergies will likely have to endure conjunctivitis every so often.


Bacterial conjunctivitis will likely be treated with eye drops containing antibiotics. Whilst your dog is recovering, they may need to wear a cone to prevent them scratching at their eyes and irritating the infection even more.

Conjunctivitis is ordinarily easy to cure and with the necessary treatment your pooch should be paw-fectly fine. However, even though it’s incredibly rare, if your dog is left without treatment, they could potentially suffer with serious long-term impacts such as impaired sight, scars, and severe eye pain.


No dog is immune to conjunctivitis, and it’s incredibly common for all dogs, however due to physical traits, there are some breeds more predisposed to the condition.

Brachycephalic (flat-faced) breeds, such as French Bulldogs and Pugs, are susceptible to many eye infections, due to the structure of their facial features. They naturally have shallow eye sockets which cause their eyes to protrude out making them more prone to eye infections.

In addition, dry eye is a common condition that leads to dogs getting conjunctivitis. It is where your dog fails to produce tears, causing dull eyes and discharge to appear around the eye. Some dogs are more susceptible to getting dry eye, meaning they are more at risk of conjunctivitis, such as Cocker Spaniels, West Highland White Terriers and Shih Tzus.


Most people probably know that conjunctivitis is highly contagious between humans, and it still is contagious in dogs, just not to the same extent.

Firstly, non-infectious conjunctivitis (caused by allergies or foreign objects etc) can’t be passed on. However, if it’s an infectious form of conjunctivitis (virus or bacterial), it can be passed onto other dogs, albeit rarely.

If you have more than one dog, try to keep their beds, bowls and toys separate until it has cleared up to prevent your other pooch from catching it.


This is incredibly unlikely, but not impossible. The same goes for you passing on conjunctivitis to your dog!

Even though this is a small possibility, still take your dog to the vet quickly and ensure you wash your hands after handling your dog to avoid any spread of the infection.


Conjunctivitis can’t be fully prevented; it’s one of those things that just happens. However, there are a few methods to reduce the chances, for example:

  • Using warm water and cotton wool to frequently clean your dog’s eyes to prevent build-up of discharge

  • Regular grooming - long hair around the eyes can cause irritation and hairs can potentially get stuck in their eye

  • Keeping things like shampoos, soaps and medicines out of your dog’s eyes to prevent irritation

  • If you think it’s conjunctivitis caused by allergies, maybe you can figure out what the irritant is and reduce their exposure to this

  • Try to stop your dog from hanging their head out of the car window as this makes them susceptible to debris getting caught in their eyes

  • Knowing the signs of conjunctivitis so you can get your dog treated promptly


Ideally, their eyes need to be bright and white. The most revealing signs of conjunctivitis are your dog’s eyes being red, swollen and producing discharge. So, if your dog’s eyes are white and crust-free then they’re looking healthy.

Also, it’s recommended to gently pull down your dog’s eye and check that the inside of it is pink rather than red and inflamed. You also want to make sure that the third inner eyelid we mentioned earlier isn’t visible.

Overall, conjunctivitis is just one of those pesky conditions that’s likely to happen to your dog at some point in their lifetime, and usually, it’s nothing to worry about if you seek treatment quickly. It’s best to just be aware of what a healthy eye looks like and what the symptoms of the infection are, so you can constantly keep an ‘eye’ out for any unusual differences in your furry friend’s eyes.