Canine Conjunctivitis

Want to know more about canine conjunctivitis? Learn this and more, including how to spot the symptoms of red-eye, causes, diagnosis and treatment.

In fact, everything you need to keep your precious Cocker Spaniel's eyes healthy!

Conjunctivitis In Dogs: What Is It?

Conjunctivitis is an inflammation of the conjunctiva, the delicate transparent layer of tissue that covers the front part of the eye, the inside of the eyelids, and your dog's third eyelid.

Headshot of a golden cocker spaniel with large, clear eyes, looking up at the camera. This photo is demonstrating healthy eyes.Example of healthy eyes, not canine conjunctivitis

The purpose of the conjunctiva is to secrete nourishment and lubricants onto the eye.

Although this delicate membrane is transparent, it actually contains tiny blood vessels, and when inflamed, it causes the eye to look swollen and bloodshot.

This is conjunctivitis, but you'll also hear it as 'pink eye' or 'red eye' for obvious reasons.

What Causes Canine Conjunctivitis?

There are many different causes of pink eye in dogs, and your vet will try to work out which one he's dealing with so that he can treat it appropriately.

Bacterial or Fungal Infections 

Canine conjunctivitis can be caused by a bacterial or fungal infection.

The culprit is likely to be the streptococcus or staphylococcus bacterium if it's bacterial.

If it's a viral infection, it could be a secondary condition of another problem such as canine distemper virus or some form of cold or flu virus. 

Both bacterial and viral conjunctivitis are highly contagious.

The eye produces mucus and pus, often causing the eyelids to crust over.

If the condition isn't treated correctly and in time, it can lead to serious eyesight problems and, in rare cases, loss of vision.


Canine conjunctivitis can also be caused by an allergic reaction to:

  • pollen;
  • dust or dust mites;
  • mould;
  • grass;
  • cigarette or wood-smoke;
  • household products;
  • perfumes;
  • a prescribed drug. 

The allergic reaction causes the membrane to become swollen and pink and produces a watery discharge and itching.

It's usually present in both eyes simultaneously, unless it's caused by a grass seed, for example, which will only affect the eye it enters.

Because it's an allergic reaction specific to each pet, it's not contagious and is often seasonal.

Injury, Irritation Or Other Eye Condition

Inflammatory canine conjunctivitis can occur following an eye injury or irritation from a foreign body, such as a piece of grit or grass seed.

It can also come about as a result of another eye disease or problem, for example:

  • dry eye (keratoconjunctivitis sicca (KCS));
  • eyelid tumours (although rare);
  • ulcerative keratitis;
  • glaucoma;
  • eyelash disorders such as distichiasis and ectopic cilia;
  • entropion.

Neonatal Conjunctivitis

Neonatal conjunctivitis is caused by a bacterial infection and affects young puppies, but it can also affect newborn puppies, even though their eyes don't open until they're around 2 weeks old!

Neonatal conjunctivitis can be present in one or both eyes simultaneously and can cause the eye to crust over, making it difficult to open. 

If the pus has nowhere to drain, it builds up behind the eyelid and can cause significant swelling.

If the eyes are open, you'll see symptoms typically associated with pink eye, such as discharge, squinting, swelling, redness etc.

If the eyes are closed, the vet will bathe them with a warm solution and open them very carefully and gently.

Once opened, the eyes can be drained and treated with an antibiotic ointment.

Neonatal conjunctivitis can be severe if not treated quickly by a vet; it can damage the cornea and, in extreme cases, lead to blindness.

Symptoms of Canine Conjunctivitis 

Symptoms will vary depending on what's causing the problem and how inflamed the eyes are, but typically will often include:

  • puffy, swollen, red eyelids;
  • bloodshot eyes;
  • runny eyes: a watery, pus, or mucous discharge;
  • swollen eye tissue;
  • closed eyes;
  • squinting and blinking in one or both eyes;
  • eyelids that stick together;
  • the third eyelid becomes visible ;
  • itching. 

If you see your dog pawing at his eyes or trying to rub his face on anything he can get near to, it's probably because his eyes are very itchy.

Do your best to stop this because any rubbing could damage his eyes (more so than actual conjunctivitis). The best solution would be to fit him with an Elizabethan collar for protection.

Diagnosis And Testing

Your vet will be keen to determine what's causing your dog's conjunctivitis so that he can treat it successfully. 

Dog detective with a magnifying glass, looking for clues of canine conjunctivitis.Just lookin' for clues!

He'll probably check your Cocker's history before carefully examining his eyes.

He'll be looking for signs of injury, a foreign body, severe eye disease and other clues to help with his diagnosis. 

If your little guy is having difficulty keeping his eyes open, he may use anaesthetic drops to numb the surface of your pet's eyes so that he can get on with the examination without distressing your dog. 

If it's a symptom of an underlying illness or severe eye disease and he only treats your dog for conjunctivitis, the underlying problem will continue to develop, and the problem will more than likely return.

It should be a case of 'treat the disease, not the symptom'.

Looking For Clues: Are Both Eyes Affected?

Canine conjunctivitis can affect either one or both eyes, depending on the cause, and this is where your vet will pick up valuable clues.

For example, if only one eye is affected with pink eye, it's unlikely to be caused by an allergy. 

It's more likely to point to either a scratch or something in your dog's eye, in which case your vet may use a fluorescent dye which, under blue light, will highlight any foreign bodies, ulcers, or abrasions.

However, if conjunctivitis is present in both eyes, it could be caused by a viral or bacterial infection, an allergy (to pollen, for example) or an environmental irritant such as cigarette or wood smoke or chemicals. 

Looking for Clues: Type of Discharge

The type of discharge from the eye will give your vet some additional clues. 

For example, if it's in both eyes and the discharge is clear and watery, an allergy may be the culprit.

If it's thick and mucus-like, it could suggest dry eyes or a fungal or bacterial problem.

Looking For Clues: Testing

Because canine conjunctivitis could be one of the symptoms of another eye disease, your vet will carry out a complete and detailed eye examination to help rule this out.

As well as inspecting the eye itself, he may check tear ducts, lashes, eyelids (including the third eyelid), and the cornea.

He may decide to test for allergies, but it's more likely that he'll try for glaucoma and other serious eye diseases.

If a diagnosis proves difficult, the vet may take cells from the conjunctiva for examination under a microscope.

Once your vet has established that the problem is conjunctivitis and understands what's causing it, he will then be able to recommend an effective treatment.

Treatment of Dog Conjunctivitis

Treating conjunctivitis in dogs very often depends on what's causing it, for example: 

Bacterial Infection:

If it's a bacterial infection, your pet will need an antibiotic, which may be given by injection, an ointment, or tablets.

Fungal Infection:

An anti-fungal ointment will be given for the treatment of a fungal infection.

Viral Infection or Existing Eye Disorder:

Treatment will vary depending on the condition, but the vet will treat the actual eye problem that's causing conjunctivitis (for example, entropion or glaucoma) and, in the meanwhile, will prescribe something to soothe the symptoms of conjunctivitis.


Treatment for canine conjunctivitis caused by an allergy usually involves flushing or washing the eye with a mild eyewash, preferably prescribed by your vet, but you can also buy over-the-counter treatments.

Your vet may also recommend antibacterial eye drops (with or without steroids, depending on how severe the condition is) to help reduce any inflammation.

He may also test for allergies to determine what's causing the allergy so that you can remove it from your pet's environment.

Injury or Irritants:

For scratches, abrasions or irritants, soothing eye drops may be all that is necessary.

Prevention of Canine Conjunctivitis

Whilst you may not be able to prevent it, you can take a few common-sense precautions to help lessen the possibility of your dog developing conjunctivitis.

Regular Eye Checks

As well as routine eye examinations with his vet, we can play our part by being vigilant by checking our Cocker's eyes when we're grooming or petting him.

Routine Eye Cleaning

I check and clear Max's eyes every morning. They're usually okay, maybe a little 'gunk' in the corner of one eye, but I take the time to remove it. 

He has a blocked tear duct (which unfortunately can't be un-blocked) so his eye waters from time to time and, as it has nowhere to drain, it runs out of the corner of his eye and onto his fur, leaving a wet streak.

It's not really a problem and it causes Max no harm, but I try to keep this area wiped dry and clean. I clean his eyes each week as part of his grooming routine.

Allergies and Irritants

Wherever possible, keep your Cocker Spaniel away from potential allergens and irritants such as chemicals, dust, pollen, smoke, grasses (in particular corn and wheat fields - I've lost count of the number of times Max has been to the vet's surgery to have a seed or a piece of chaff removed from his ear!)

And don't let your dog ride in the car with his head out of the window. I suspect we've all been guilty of that at some time, but it's a recipe for disaster. He could get hit (or stung) in the eye by an insect, grit and other airborne nasties. It's just not worth the risk.

I realize there's only so much we can do to protect our pets from allergens and irritants...they're Cocker Spaniels, for goodness sake! They love to romp around in fields and the undergrowth.

Dogs will be dogs, and we can't wrap them in cotton wool, but we can at least try anyway, can't we? 


By staying up to date with all vaccinations, we can protect our pets against other canine diseases that can cause conjunctivitis, such as distemper - one less thing to worry about!

Canine Conjunctivitis: Summary

So, whilst we can't actually prevent dog conjunctivitis, there are things that we can do to reduce the risk for our pets.

Staying in touch with the vet and making sure your pooches eyes are examined regularly is the first step towards catching eye problems early, so make sure your Spaniel sees his vet at least once a year.

You can also play your part at home by checking your pet's eyes daily. Clear any gunk from the corners and gently wipe around the eye area using a piece of cotton wool soaked in saline solution or an eye cleaner recommended by your vet. 

Keep the dreaded pink eye at bay!

Photo credit: Canine Conjunctivitis:

Photo of Dog detective: My Cute Graphics