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Conjunctivitis in Dogs (Pink Eye)

What is Conjunctivitis in Dogs?

Conjunctivitis, commonly known as pink eye, is a prevalent condition in dogs, akin to its occurrence in humans. The term conjunctivitis refers to the inflammation or swelling of the conjunctiva, the tissue enveloping the eyeball and eyelids. This tissue, comprising a layer of cells that produce mucus, is known as a mucous membrane.

Dogs possess a nictitating membrane, often referred to as a third eyelid, situated at the inner corner of each eye, which consists of conjunctival tissue. Normally, healthy conjunctiva appears pink, though it may be pigmented in certain dog breeds. In cases of inflammation, such as conjunctivitis, the mucous membranes swell, causing itching and a brighter pink or red hue.

Conjunctivitis manifests in different forms:

Allergic Conjunctivitis: Any dog breed may experience allergic conjunctivitis, particularly those predisposed to atopic dermatitis, a hypersensitivity to various common environmental substances. This condition commonly affects young adults but can occur at any age. Environmental allergens like dust, pollen, molds, mites, perfumes, and shampoos, as well as food allergens (typically certain proteins) and genetic predispositions to allergies (atopy), frequently contribute to allergic conjunctivitis.

Viral Conjunctivitis: Dogs of any breed may contract viral conjunctivitis upon exposure to viruses that cause inflammation in the eye membranes. These viruses tend to be highly contagious and may take 3 to 4 weeks to fully resolve. Examples of viruses responsible for these symptoms in dogs include canine distemper virus and canine herpesvirus.

Bacterial Conjunctivitis: Primary bacterial conjunctivitis is rare in dogs, with no known predispositions based on age, gender, or breed. Instead, secondary bacterial infections in the eyes typically arise due to underlying medical issues such as chronic dry eye, eyelid abnormalities, or corneal ulceration (scratches to the outer layer). Staphylococcus or Streptococcus bacteria, both highly contagious for dogs, are the most common culprits behind bacterial conjunctivitis.

Other medical conditions that can increase a dog’s susceptibility to conjunctivitis include:

  • Immune-mediated disorders
  • Tumors affecting the eyelid or conjunctiva
  • Keratoconjunctivitis sicca (dry eye)
  • Eyelid abnormalities like entropion (inward rolling of the lower eyelid), ectropion (outward rolling of the lower eyelid), or abnormal eyelash growth
  • Blocked tear ducts
  • Eye trauma caused by smoke, foreign objects, or pollutants
  • Glaucoma (elevated eye pressure)
  • Uveitis (inflammation causing decreased eye pressure)
  • Breed-specific conditions such as nodular episcleritis in Collies
  • Parasitic infestations (though rare)


Symptoms of conjunctivitis in dogs include red and swollen eye membranes, commonly known as pink eye. Affected dogs often experience itching, burning, or pain, leading them to rub their faces on rugs or with their paws. Squinting or excessive blinking is common due to eye discomfort. Typically, there is a cloudy white, yellow, or greenish mucus-like discharge from the affected eye(s). Green or yellow discharge usually indicates a bacterial infection, while clear or white discharge is more likely to result from allergies. Conjunctivitis typically affects both eyes unless it stems from trauma, eyelid abnormalities, blocked tear ducts, or tumors. Additional clinical signs may include generalized itching, hair loss around the eyes, nasal discharge, sneezing, coughing, and lethargy.


The causes of conjunctivitis in dogs can vary and may include allergies, viral infections, bacterial infections, immune system issues, anatomical factors specific to the dog, trauma, or cancer. Regardless of the underlying cause, the clinical signs often remain consistent. It’s typically necessary to consult your veterinarian for a thorough examination to determine the cause.


To diagnose conjunctivitis in dogs, veterinarians conduct a comprehensive physical examination along with a detailed ophthalmic assessment to identify any underlying medical issues contributing to the condition. The primary objective of diagnosis is to determine the cause of conjunctivitis and assess the extent of eye damage.

The ophthalmic examination includes:

  • A thorough inspection of the surrounding eye structures, encompassing the eyelids, fur around the eye, eyelashes, third eyelid, and tear ducts.
  • Schirmer tear testing, a non-invasive procedure to measure tear production in both eyes.
  • Fluorescein stain testing, another non-invasive test to detect damage to the cornea, the outer layer of the eye, such as scrapes or cuts. This involves applying a yellowish stain to the eye and using a special light in a darkened room to reveal any underlying damage.
  • Intraocular pressure testing to assess the pressure within both eyes, aiding in the diagnosis of conditions like glaucoma and uveitis.

Further diagnostic measures may include bacterial culture and sensitivity testing, conjunctival scraping or biopsy, allergy testing, viral testing, ultrasound of the eyeball, and tear duct flushing as deemed necessary based on the examination findings.


Treatment for conjunctivitis in dogs varies based on the underlying cause:

  • Allergic conjunctivitis is typically addressed with steroid-containing eye drops or ointments. In some cases, oral steroids and antihistamines may be prescribed to alleviate systemic inflammation. Preventive measures such as avoidance of allergens, allergic skin testing, flea preventatives, environmental adjustments, and dietary trials may be recommended by the veterinarian.
  • Bacterial conjunctivitis is usually treated with topical antibiotics, occasionally supplemented with oral antibiotics and anti-inflammatory drugs depending on the infection’s severity.
  • Viral conjunctivitis often resolves with time and may benefit from oral antioxidants to bolster the immune system. Additionally, oral or topical antiviral medications may be prescribed in certain cases.
  • Dogs diagnosed with eyelid or eyelash abnormalities may require surgical correction to prevent recurring issues.
  • Dogs suffering from chronic dry eye necessitate lifelong medication to stimulate tear production.
  • Dogs with immune-mediated conditions typically require long-term immunomodulatory medications, administered orally and topically, to regulate the immune system.


Preventing further harm to the eye while addressing the underlying issue is crucial for the healing process. Using an Elizabethan collar or pet cone can prevent your dog from rubbing their face or scratching their eyes, which could lead to abrasions or perforations in the cornea.

Frequent veterinary check-ups are typically advised to monitor healing progress and adjust treatment if needed. If clinical signs fail to improve, deteriorate rapidly, or recur as chronic problems, your veterinarian may suggest referral to a veterinary ophthalmologist or dermatologist for specialized care.

Home Remedies for Conjunctivitis in Dogs

Home remedies can offer relief from discomfort and maintain eye cleanliness in dogs with conjunctivitis, although they typically do not address the underlying medical issue. Using sterile saline eye wash solutions gently once or twice daily can help clean discharge from around your dog’s eye and remove dust, pollen, and debris.

Before attempting an eye flush at home, it is imperative to consult your veterinary team to prevent any inadvertent harm to the eye.

Certain holistic products may be applied topically around the eye or administered orally to prevent tear duct blockage, a potential cause of conjunctivitis in some dogs. However, it is essential to discuss these options with your veterinarian before initiating any treatment for your dog’s eye conditions.

Living and Management

Recovery from conjunctivitis in dogs is typically excellent for most cases. However, chronic, recurrent, or severe instances may have a guarded prognosis, which depends on the underlying cause. Managing chronic or recurring cases often involves lifelong therapy aimed at controlling underlying allergies, promoting tear production, or addressing systemic or ophthalmic immune-mediated conditions. Regular veterinary appointments may be required to determine the most effective treatment plan and evaluate the response to therapy.

Conjunctivitis in Dogs FAQs

Is conjunctivitis in dogs contagious?

Conjunctivitis in dogs can be highly contagious if it’s viral or bacterial. However, if your dog is fully vaccinated, the chances of viral transmission decrease. Viral conjunctivitis isn’t transmissible to humans. It’s essential to consult your veterinarian to determine the recommended vaccines for your pet. While primary bacterial conjunctivitis is rare, it can potentially spread to humans through direct contact. Proper hand hygiene, including handwashing before and after touching your dog, is crucial if bacterial conjunctivitis is diagnosed.

Will conjunctivitis in dogs go away by itself?

While some forms of canine conjunctivitis may resolve spontaneously in dogs with robust immune systems, most cases require treatment to prevent chronic eye changes and achieve complete resolution of symptoms like squinting, redness, pain, and discharge.

What happens if conjunctivitis in dogs is left untreated?

Leaving conjunctivitis untreated can lead to inflammation affecting the cornea, resulting in scarring, chronic pain, ulceration, and potentially uveitis (inflammation inside the eye). Apart from being painful, this scenario can predispose your dog to lifelong chronic infections.

How long does conjunctivitis in dogs last?

The duration of clinical signs varies depending on the underlying cause. Bacterial conjunctivitis typically resolves fully within 5 to 7 days with appropriate treatment. Viral conjunctivitis may take 3 to 4 weeks for complete resolution. Allergic conjunctivitis persists until the underlying allergen is identified and removed. Chronic dry eye and immune-mediated conditions often require lifelong therapy for management.

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