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Conjunctivitis in Dogs: Signs, Treatment & Causes (Vet Answer)


Mar 14, 2023
dog with conjunctivitis in the eye


dog with conjunctivitis in the eye
Dr. Iulia Mihai Photo

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Does your dog have red, inflamed, and watery eyes without other clinical signs? They probably have conjunctivitis, a common eye problem in dogs. Also called pink eye, it’s a condition that can occur in any dog breed, regardless of age. It is important to note that once conjunctivitis has localized in one eye, it can easily spread to the other eye if left untreated.

When you notice changes in your dog’s eyes, it is important to contact your veterinarian because conjunctivitis could be a clinical sign of more severe diseases, such as canine distemper or Lyme disease. If left untreated for too long, it can even lead to permanent blindness.


What Is Conjunctivitis in Dogs?

Conjunctivitis is the inflammation of the ocular conjunctiva, the membrane that covers the eyeball and lines the inner surface of the eyelids. This membrane secretes mucus and is similar to the mucous membrane of the mouth and nose. The conjunctiva also covers the third eyelid.

When this membrane becomes inflamed as a result of an eye condition or injury, the tissue becomes red, warm, swollen, and sometimes painful.

Dogs with conjunctivitis have red eyes with cloudy whitish or yellow-green secretions that dry and stick to the eyelids. Depending on the color of the secretions, veterinarians can tell if it is a bacterial infection, an allergy, or something else.

Conjunctivitis can be primary or secondary (caused by other medical conditions) and affect one or both eyes. This condition can lead to itching and hair loss around the eyes, coughing, sneezing, and a runny nose.

It is not considered dangerous but can be accompanied by considerable pain and other clinical signs that could stress your dog. In cases where it remains untreated for a long time, conjunctivitis can lead to permanent blindness.

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What Are the Signs of Conjunctivitis in Dogs?

Conjunctivitis can be easily recognized in pets, especially if their owners have dealt with it before.

Among the most common signs are:

  • Red, inflamed eyes, especially the white part of the eyes
  • Prominent third eyelid
  • Mucous or purulent secretions that are cloudy white or greenish yellow
  • Swollen eyeballs, and due to the accumulation of fluid, the eyes appearing larger
  • Frequent blinking
  • Rubbing their eyes with their paws because of pain and/or itching
  • The eyelids sticking together

In addition, dogs will keep their eyes partially or completely closed and may experience discomfort in the light due to the itching caused by the inflammation.

If chronic conjunctivitis develops, blisters (follicles) can form on the conjunctiva, which will further irritate the dog’s eyes.

Cross section of a dog's eye
Image Credit: Petkeen.com

What Are the Causes of Conjunctivitis in Dogs?

Conjunctivitis can occur from several causes and can be primary or secondary, being a manifestation or consequence of other pathologies, which in some cases, can be severe.

Bacterial Causes

Conjunctivitis can be caused by dry eye syndrome (keratoconjunctivitis sicca), which is also known as the primary condition of conjunctivitis. In some cases, it can be associated with bacterial infections, and the signs are noticed when dogs open their eyes, as there are yellow-green purulent secretions.

Viral Causes

The main viral cause of conjunctivitis in dogs is canine distemper. Besides conjunctivitis, dogs show other clinical signs such as nasal discharge, fever, coughing, vomiting, and lethargy. It often leads to death. Respiratory infections and dog flu (canine influenza) can also lead to conjunctivitis.

dog eyelid closeup shot
Image Credit: Sabrinasfotos, Pixabay

Parasitic Causes

In some cases, when dogs are infested with the parasite Borrelia burgdorferi from ticks (Lyme disease), they can also develop conjunctivitis. Other clinical signs of Lyme disease are fever, joint pain, apathy, and loss of appetite.

Immunological Causes

These are represented by:

  • Various allergies
  • Diseases of the blood vessels
  • The lack of a normal tear film that leads to dry eye syndrome
  • Diseases in which the body’s immune system attacks its own tissues

Allergic conjunctivitis can occur in any dog breed, with young adults being more prone. The factors that favor the occurrence of this condition are dust, food allergies, certain medicines, mold, and certain essential oils toxic to animals.

Secondary Causes

The presence of a foreign body in the moist tissues of the eye (dust, wood chips, shards, etc.) can lead to conjunctivitis. Pollen, chemicals, or eye medications can also cause conjunctivitis in dogs.

Conjunctivitis can be a manifestation of certain eye diseases such as keratitis, corneal lesions, uveitis, and glaucoma.

dog eyes infection
Image Credit: Tatiane Silva, Shutterstock

Can Conjunctivitis Spread to Other Pets?

If your dog’s conjunctivitis is viral or bacterial (from canine distemper, dog flu, etc.) it can be transmitted to other pets. Non-infectious conjunctivitis is not contagious.

Infectious conjunctivitis can spread through direct contact with another infected animal or the environment and accessories of the sick animal. As a result, if your dog has viral or bacterial conjunctivitis, their accessories (water and food bowl, toys, and bedding) must not come into contact with a healthy animal. If you have several dogs, quarantine the sick one, and take the others to the vet for a check-up to make sure they are healthy.

How Do I Care for a Dog With Conjunctivitis?

If you notice that your dog has signs of conjunctivitis, take them to the vet because it can be something more severe than a simple eye inflammation. In cases where conjunctivitis is secondary to other ocular or systemic diseases, the veterinarian must treat the primary condition that caused the inflammation in question. If your dog has viral or bacterial conjunctivitis, it is best to keep them isolated and away from healthy animals.

If your dog’s conjunctivitis is caused by a foreign body, remove it carefully and completely. Contact the veterinarian if the foreign body has entered the eye or you cannot remove it. If your dog has developed allergic conjunctivitis, avoid letting them come into contact with the irritating substance or allergen (if you know what caused your pet’s conjunctivitis).

Avoid air currents because they could dry out your dog’s eyes and cause inflammation. Check your dog’s eyes often, and clean the secretions whenever you notice them. You can do this with sterile gauze damped with saline solution or warm water.

Use only the medicines recommended by your veterinarian, and follow their instructions and advice closely.

vet examines eye of a dachshund dog
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Frequently Asked Questions (FAQs)

Can Conjunctivitis in Dogs Heal on Its Own?

Conjunctivitis does not heal by itself, even if the non-infectious version is not a severe condition. This condition may indicate a more serious health problem, so you should talk to the vet. If left untreated, conjunctivitis can lead to more severe complications, such as permanent blindness.

Should I Walk My Dog If They Have Conjunctivitis?

You can walk your dog without problems if the conjunctivitis is not viral or bacterial, i.e., contagious. Viral infectious conjunctivitis may not be contagious to you, but it is to other dogs. Conversely, bacterial conjunctivitis can be contagious to you too. If your dog has been diagnosed with infectious conjunctivitis, you can walk them, but be careful not to let them come into contact with healthy dogs or their accessories.

Do Dogs With Conjunctivitis Feel Sick?

If your dog’s conjunctivitis is primary, your pet should not feel sick. Dogs feel sick when conjunctivitis is secondary to other conditions, such as canine distemper, Lyme disease, dog flu, etc. In these cases, your dog will show other clinical signs besides conjunctivitis, such as fever, runny nose, apathy, or lack of appetite.



Most dogs develop conjunctivitis at least once in their lives. The condition can be primary when it is caused by dry eyes or secondary when it occurs alongside other clinical signs in systemic or immune disorders. Dogs with conjunctivitis generally have red, inflamed, and watery eyes with cloudy or purulent secretions. They can also present itching and sometimes pain. Depending on the causative agent of your dog’s conjunctivitis, the vet will prescribe the appropriate treatment. Conjunctivitis can be treated, and if left untreated for a long time, it can lead to permanent blindness.

Featured Image Credit: Alexandr Jitarev, Shutterstock

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