If Your Dog Keeps Rubbing Its Eyes — Causes of Conjunctivitis and a Guide to Using Eye Drops

Eye HealthDiseasesMeongsiljang Veterinary Advisory Board

Canine conjunctivitis is an eye condition in which the conjunctiva becomes inflamed, leading to redness, increased discharge, and excessive tearing. Here’s a clear, pet-owner-friendly overview of how symptoms vary by cause and how to properly use eye drops.

What Is Canine Conjunctivitis?

A close-up of a puppy’s eye with slightly reddened conjunctiva

Canine conjunctivitis is an eye condition characterized by inflammation of the conjunctiva, the thin mucous membrane lining the inner eyelids and covering the whites of the eyes. The most critical step is to quickly identify the underlying cause. Even when symptoms like redness and discharge appear similar, the appropriate eye medication varies significantly depending on whether the cause is bacterial, allergic, or due to dry eye. Many cases progress to corneal ulcers when owners self-diagnose and administer over-the-counter eye drops found online. Therefore, if symptoms persist for more than 24 hours or if your dog cannot open its eyes, please visit a veterinary clinic immediately.

Why Does Conjunctivitis Occur? — 5 Main Causes

Canine conjunctivitis isn’t caused by a single factor; it develops when various irritants affect the conjunctiva. This is why pet owners often find it confusing. - Bacterial infection: Staphylococcus and Streptococcus are the most common culprits. Thick, yellow discharge is a key sign. - Allergies: Reactions to pollen, house dust mites, or proteins in pet food. Both eyes typically become itchy at the same time. - Viral infections: Distemper and adenovirus. These often appear in puppies alongside respiratory symptoms. - Foreign bodies and irritation: Grass seeds or abnormal eyelashes (distichiasis) can scratch the conjunctiva. - Keratoconjunctivitis sicca (KCS): Insufficient tear production leads to chronic conjunctivitis.

Symptom Checklist — Suspect Conjunctivitis If You See These Signs

These are signs you can check at home. If two or more apply, suspect conjunctivitis. - Redness: The whites of the eyes turn pink or red. - Increased eye discharge: Significant if the eyes are stuck shut in the morning. - Discharge color: Clear (allergies or viral infection), yellow or green (bacterial involvement), brown (chronic irritation) - Tearing: The fur beside the nose is constantly damp. - Eye rubbing: Rubbing with the front paws or rubbing the face on the floor. - Eyelid swelling: Swelling causes the eyes to remain partially closed. - Third eyelid exposure: The pink membrane on the inner corner of the eye is more visible than usual.

Comparison images of a dog’s eyes showing the main symptoms of conjunctivitis

🚨 Signs Requiring Immediate Veterinary Attention

If any of the following apply, it is likely not simple conjunctivitis. The early signs can closely resemble emergency conditions such as corneal ulcers, glaucoma, or uveitis. Do not administer over-the-counter eye drops on your own; visit a veterinary clinic immediately. - Your pet cannot open its eyes at all, or keeps one eye closed as if squinting. - You see white spots or cloudy areas on the black part of the eye (cornea). - Redness has worsened within 24 hours. - Your pet is vigorously rubbing its eyes, risking self-injury. - One eye has suddenly become swollen.

How Is It Diagnosed at the Veterinary Clinic?

With conjunctivitis, identifying the underlying cause is far more important than simply noting the diagnosis. Veterinarians typically proceed with the following tests in a stepwise manner: - Slit-lamp examination: Magnifies the conjunctiva and cornea to check for foreign bodies or ulcers. - Fluorescein staining test: Uses fluorescent dye to detect any corneal abrasions. This is essential before starting conjunctivitis treatment. - Schirmer tear test: Measures tear production over one minute to rule out dry eye (keratoconjunctivitis sicca). - Conjunctival cytology and culture: Identifies the specific pathogen and its antibiotic sensitivity in cases of chronic or recurrent conjunctivitis. Never attempt self-medication. Applying steroid eye drops without prior fluorescein staining can cause corneal ulcers to worsen rapidly and severely.

Treatment Methods — Eye Drops Vary by Cause

Treatment for conjunctivitis primarily relies on eye drops. However, using the wrong drops without knowing the underlying cause can actually worsen the condition, as the appropriate type of medication varies significantly depending on the cause. - Bacterial: Antibiotic eye drops are used. For the most effective treatment, medication should ideally be selected based on cytology, smear tests, and culture and sensitivity testing. - Allergic: Treatment involves antihistamine and anti-inflammatory eye drops (steroidal or non-steroidal), along with environmental management to avoid the triggering allergens. - Viral: Most cases improve with appropriate care. If a secondary bacterial infection is present, antibiotics are used in conjunction with other treatments. - Keratoconjunctivitis Sicca (Dry Eye): Artificial tears protect the corneal surface, while immunomodulatory drops like cyclosporine are used for long-term management, sometimes for life. - Foreign Bodies or Eyelashes (Distichiasis): Removing the underlying cause is the priority, with eye drops serving only as an adjunct. Particularly when corneal ulcers are present, indiscriminate use of steroid eye drops can delay healing and cause further corneal damage. Therefore, it is essential to follow your veterinarian’s prescription exactly and complete the full course of treatment, even if symptoms improve, to minimize the risk of recurrence.

A pet owner administering eye drops to their dog

Comparison Table of Symptoms and Treatments by Cause

Item	Bacterial	Allergic	Viral	Keratoconjunctivitis sicca
Discharge color	Yellow/green	Clear	Clear→yellow	Sticky mucoid
Bilateral/unilateral	Mainly unilateral	Bilateral	Bilateral	Bilateral, chronic
Itching	Moderate	Severe	Mild	Moderate
Main eye drops	Antibiotics	Antihistamines/steroids	Antibiotics (secondary)/antivirals	Artificial tears/cyclosporine
Treatment duration	7–14 days	With environmental management	10–21 days	Lifelong management

An accurate diagnosis requires veterinary judgment after fluorescein staining and tear production testing.

Home Care Tips

Recovery is faster when you care for your pet at home alongside veterinary treatment. - Cleaning eye discharge: Use gauze moistened with lukewarm water to wipe from the inner corner outward, using a fresh piece each time. Do not use the same gauze on both eyes. - Spacing eye drops: If prescribed two or more types, wait 5–10 minutes between applications. Applying them immediately one after another will wash out the first medication. - Check refrigeration requirements: Many antibiotics and immunomodulators require refrigeration. Always check the label. - Elizabethan collar: To prevent rubbing, keep the collar on until fully recovered to significantly reduce the risk of recurrence. - If allergies are suspected: After walks, wash your pet’s paws and face with lukewarm water to remove pollen.

Breed-Specific Precautions — Dogs More Susceptible to Conjunctivitis

Brachycephalic and long-haired breeds are anatomically more prone to conjunctivitis. Please check the area around your pet’s eyes once or twice a week as part of your regular care routine. - Shih Tzu, Pekingese, Pug: Their protruding eyes are more susceptible to dryness and irritation from foreign particles. - Bulldog, Boxer: They are prone to entropion (a condition where the eyelid rolls inward, causing eyelashes to rub against the eye), which can lead to chronic irritation. - Cocker Spaniel: This breed is known to be susceptible to keratoconjunctivitis sicca (dry eye syndrome caused by insufficient tear production), so it’s important to regularly monitor tear production. - Maltese, Yorkshire Terrier: Their long hair can poke into the eyes, potentially causing chronic conjunctivitis. - Poodle: Allergy-related conjunctivitis, particularly associated with atopy, is relatively common in this breed.

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can I use human eye drops (artificial tears) on my dog?

Preservative-free single-use artificial tears can be used temporarily, but human eye drops containing antibiotics or steroids should never be used, as they can worsen corneal ulcers. It is essential to visit an animal hospital within 24 hours.

Can conjunctivitis be transmitted to humans?

Most cases of conjunctivitis in dogs are not contagious to humans. However, chlamydia and certain bacteria can rarely be transmitted to people with weakened immune systems, so please wash your hands after administering eye drops.

I’ve been applying the eye drops for a few days, but there’s no improvement. Should we switch to a different medication?

Antibiotic eye drops typically begin to show improvement within 48 to 72 hours. If there is no change after three days, the underlying cause may be different—such as allergies, dry eye (keratoconjunctivitis sicca), or a foreign body—or the infection may be caused by antibiotic-resistant bacteria, so a follow-up veterinary visit is essential. Do not change medications on your own.

My pet’s conjunctivitis keeps coming back. Why is that?

Common causes of recurrent conjunctivitis include: 1) stopping eye drops prematurely without veterinary guidance, 2) undiagnosed dry eye (keratoconjunctivitis sicca), 3) structural issues such as entropion or abnormal eyelashes, and 4) unaddressed environmental allergens. If the condition recurs three or more times, be sure to have your pet undergo tear production testing and an examination of eyelid structure.

Is there a way to prevent it?

After walks, gently wipe around the eyes with lukewarm water-soaked gauze, regularly groom any hair that may poke into the eyes, schedule an annual ophthalmic exam, and keep up with core vaccinations such as distemper. For brachycephalic and long-haired breeds, make it a habit to perform a self-check once a week.

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References

[1] Esson DW, Calvarese S. Clinical Atlas of Canine and Feline Ophthalmic Disease, 2nd Edition, John Wiley & Sons, 2022

[2] Schaer M, Gaschen F. Clinical Medicine of the Dog and Cat, 4th Edition, CRC Press, 2017

[3] Robinson NJ, et al. 100 Top Consultations in Small Animal General Practice, Wiley-Blackwell