Conjunctivitis in dogs


Conjunctivitis means inflammation (swelling) of the ‘conjunctiva’ and can be caused by many different conditions. The conjunctiva is a very thin layer of tissue that covers the inside of the eyelid and runs across the front of the eye. Conjunctivitis causes red, itchy, weepy eyes.

Always contact your vet if you notice anything wrong with your dog’s eyes – they are too important to ignore. If your dog suffers with conjunctivitis regularly, your vet will investigate why.


Conjunctivitis can affect one or both eyes. Common signs include:

  • Pink or red eye(s)
  • Weepy eye(s)
  • Swollen eye(s)
  • Closed eye(s)
  • Rubbing their eye(s) or face
  • A cloudy appearance to eyes (blue eyes)
  • Blinking more than usual
  • Off food, unwell in themselves.
Illustration showing conjuctiva in dogs

The conjunctiva is a very thin layer of tissue that covers the inside of the eyelid.

When to contact your vet

Contact your vet if you notice any of the symptoms above or if you have a suspicion there is something wrong with your dog’s eye(s). If conjunctivitis is left too long without treatment, it can lead to serious problems or even loss of an eye.

If your dog suffers with conjunctivitis regularly, your vet will check for any conditions that might be causing it.

You know your dog best. If they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.

Causes of conjunctivitis in dogs


  • Your dog’s eyes are likely to become inflamed if they come into contact with something irritating for example smoke, dust, sand or acid.

Bacterial infection

  • Many bacteria can cause eye infections.
  • If your dog suffers regularly from bacterial infections in their eyes, there is likely to be a reason (such as dry eye or an in-growing eyelash).


  • Allergies such as atopic dermatitis (atopy) often affect the skin around the eyes. Dogs with atopy suffer with conjunctivitis much more often than dogs with healthy skin.

Dry eye (Keratoconjunctivitis sicca)

  • Dry eye is a very common cause of conjunctivitis in dogs.
  • Dogs with dry eye don’t produce enough tears which means their eyes become dry and inflamed.

Eye ulcer (corneal ulcer)

  • Eye ulcers are injuries (such as scratches or grazes) on the front of the eye.
  • Eye ulcers can become very serious if not treated quickly.

Eyelash disorders

  • Eyelash disorders such as eyelashes growing from the wrong place or in the wrong direction.

Eyelid disorders

  • Eyelid disorders such as eyelids that turn in (entropian) or are too baggy (ectropian).


  • Glaucoma is increased pressure in the eye. An eye with glaucoma will usually look cloudy and as though it is bulging.

Exposure keratitis

  • Exposure keratitis is a condition which means the eyelids don’t protect the front of the eye properly, it becomes dry and inflamed as a result.
  • Exposure keratitis is a very common condition in short-nose breeds of dog (such as the Shih Tzu).

Something stuck in the eye

  • Something stuck in the eye (i.e. a grass seed).


  • Uveitis is inflammation inside the eyeball.

Lens luxation

  • Lens luxation is when the lens (a solid disc inside the eye) dislodges into the front of the eye.

Lumps and swellings in and around the eyes

  • Lumps and swellings around the eyes can cause irritation and inflammation.

Pannus (chronic superficial keratitis)

  • Pannus is a condition that causes a dog’s own immune system to attack the front of the eye causing inflammation.

Viral infection

  • Some viruses can cause conjunctivitis.
  • Fortunately, they are very rare, probably because most dogs are vaccinated against them (e.g. Distemper virus and Adenovirus-1).
  • Remember to have your dog regularly vaccinated to protect them against conditions like this.


Treatment for conjunctivitis depends on the cause. Read articles on the conditions above for more information on each cause.

What if it doesn’t get better?

If your dog keeps getting conjunctivitis, they will need investigation by your vet. Investigations may include swabs, tear measurement or perhaps referral to a specialist ophthalmologist (eye vet).

Some conditions that cause conjunctivitis need lifelong treatment (for example atopy or dry eye).

Published: October 2018

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Written by vets and vet nurses. This advice is for UK pets only. Illustrations by Samantha Elmhurst.