Dog Conjunctivitis (Dog Eye Infection): Causes, Symptoms, Diagnosis and Treatment

Dog conjunctivitis, or dog pink eye, is inflammation of the conjunctiva. The conjunctiva is the protective, lubricating, thin tissue layer lining the eyelid interior and the white, visible part of the eyeball. 

Conjunctivitis in dogs is widespread and occurs independently or as a secondary systemic disease symptom. The inflammation affects one or both eyes, depending on the underlying trigger. 

Common risk factors for conjunctivitis include allergies, infections, trauma, eyelid abnormalities, tear duct problems, airborne irritants, tumors, and systemic disorders. 

Dog conjunctivitis clinically manifests with eye redness or inflammation, swelling and puffiness, eye discharge, blinking and squinting, rubbing and pawing, sensitivity to light, increased tear production, crust formation, changes in eye appearance, and signs of discomfort. 

Diagnosing conjunctivitis is straightforward, and the veterinarian orders various tests, including inspection, ophthalmoscopy, tonometry, Schirmer tear test, fluorescein staining, conjunctival scraping or swabbing, and biopsy to diagnose underlying causes. 

Dog conjunctivitis is treatable with topical medications and surgery. During treatment, the dog wears an Elizabethan collar to prevent eye damage, while using CBD oil relieves pain and inflammation. 

What is Conjunctivitis in Dogs?

Conjunctivitis in dogs is inflammation of the conjunctiva or conjunctival membranes. The conjunctiva is the soft, thin, and clear tissue lining the inside of the dog’s eyelids and the white portion of the eye or sclera. 

Dog conjunctivitis, known as pink eye, manifests in one or both eyes. Pink eyes are painful and itchy, making dogs light-sensitive and prone to squinting and pawing at their eyes. 

Is Dog Conjunctivitis a Common Dog Eye Infection?

Yes, dog conjunctivitis is a common dog eye infection. “Pink eye, known as conjunctivitis in the veterinary community, is quite common in dogs,” reports the American Kennel Club (AKC) in a 2024 online article titled “Can Dogs Get Pink Eye?”

Conjunctivitis or pink eye is widespread in dogs and does not target dogs of a specific breed, age, or gender. The inflammation, based on the underlying trigger, affects one or both eyes. 

What is Inflammation of Conjunctiva in Dogs Health?

Inflammation of conjunctiva in dogs health is irritation of the conjunctival membranes covering the inside of the eyelids and the sclera. 

The conjunctiva produces mucus, which mixes with water from the lacrimal glands and oil from the meibomian glands, creating tears. 

The two main roles of conjunctival secretion are eye protection and lubrication. The conjunctiva blocks irritants and microbes from entering the eye while locking in moisture and lubrication. 

Dog conjunctivitis is when the conjunctiva is inflamed, affecting its ability to protect and lubricate the eye. 

What Differentiates Conjunctivitis in One Eye from Both Eyes in Dogs?

The underlying trigger differentiates conjunctivitis in one eye from conjunctivitis in both eyes in dogs. 

Trauma, foreign objects, glaucoma, tear sac inflammation, and neoplastic diseases affect one eye, resulting in unilateral conjunctivitis. Allergies, infections, and systemic disorders cause bilateral dog conjunctivitis, affecting both eyes. 

Does Dog Conjunctivitis Lead to Blindness?

Yes, conjunctivitis leads to blindness if left untreated. Conjunctivitis is a manageable condition that progresses in severity over time when ignored. 

Inflammation spreads from the conjunctiva to other parts of the eye. Inflammation causes damage, which is painful and culminates in vision problems or blindness in severe cases. 

The two most common complications of untreated conjunctivitis increasing the risk of blindness are cataracts and glaucoma. 

What are the Risk Factors that Cause Conjunctivitis in Dogs?

The risk factors that cause conjunctivitis in dogs are listed below. 

• Infection: Bacterial and viral agents cause dog conjunctivitis. Infections are common in young, elderly, and immune-compromised dogs. Bacterial infections occur when Streptococcus or Staphylococcus bacteria from other body parts reach the eyes. Common viral causes are canine distemper virus, canine influenza, and canine herpes virus.   
• Allergies: Airborne allergens irritate the dog’s eyes, causing inflammation. Allergic dog conjunctivitis is described as an “underdiagnosed and undertreated” condition in a study, “Diagnostic Approach and Grading Scheme for Canine Allergic Conjunctivitis,” published in BMC Veterinary Research in 2023. 
• Traumatic Injuries: Trauma includes physical injuries to the sensitive structures of the eyes and damage caused by foreign objects, like sand, dirt, or plastic.
• Irritants: Airborne irritants, such as dust and cigarette smoke, cause dog conjunctivitis. Certain dogs are more sensitive to irritants than others.  
• Dry Eye: Dry eye, or keratoconjunctivitis sicca (KCS), is a specific inflammation caused by a lack of tear production or obstruction of the tear gland. 
• Eyelid Disorders: Abnormal eyelid conformation, such as entropion and ectropion, and eyelash disorders irritate the eye's surface, resulting in dog conjunctivitis.
• Growths and Tumors: Growths and tumors on or around the eyes and eyelids cause pink eye. Chalazion is a common type of growth, while meibomian gland adenomas, papillomas, and melanomas are tumors. 
• Health Conditions: Certain systemic diseases affecting the dog’s immunity, like autoimmune conditions, increase the risk of conjunctivitis due to lowered defense mechanisms. 

Can Dogs Get Pink Eye at Home?

Yes, dogs can get pink eye at home. Dog conjunctivitis triggers are ubiquitous inside and outside the home. 

Environmental irritants like smoke and dust seep into the house, with trauma occurring at home in some cases.  

Congenital eye problems in dogs increase the risk of conjunctivitis and are unrelated to going outside. 

What Type of Breed is More Prone to Conjunctivitis in Dogs?

The brachycephalic type of breed is more prone to conjunctivitis in dogs. Brachycephalic dogs have short noses paired with large, round eyes. 

The unusual facial anatomy of flat-faced dogs makes them susceptible to trapped debris and dirt in the eyes, which cause inflammation. Bulldogs, Boxers, Pugs, and Shih-Tzus are standard brachycephalic breeds. 

Other breeds at risk of developing dog conjunctivitis include Retrievers, Miniature Schnauzers, Poodles, Hounds, and Cocker Spaniels. 

What are the Symptoms of Conjunctivitis in Dogs?

The symptoms of conjunctivitis in dogs are listed below. 

• Redness and Inflammation: Redness is a telltale sign of inflammation, prompting the term “pink eye” for dog conjunctivitis.  
• Swelling and Puffiness: Swelling is a sign of inflammation and makes the dog’s eyes appear puffy or semi-closed in severe cases. 
• Eye Discharge: Inflamed conjunctiva in dogs produces more secretions, resulting in eye discharge. 
• Blinking and Squinting: Blinking is repeated eyelid movement, and squinting is staring through partially closed eyes, usually due to photosensitivity.  
• Rubbing and Pawing: Rubbing and pawing refer to the dog’s attempts to remove the irritation source around the eyes using its limbs.  
• Sensitivity to Light: Heightened sensitivity to light or photophobia results in severe eye pain or aversion toward bright light sources and well-lit environments. 
• Increased Tear Production: Increased tear production, or epiphora, is the overactivity of the lacrimal glands in response to irritation or inflammation.   
• Crust Formation: Crust formation is the development of rigid and sticky masses of dried tear duct discharge.  
• Changes in Eye Appearance: Local processes cause the inflamed eye or eyes to change in color, size, and overall appearance. 
• Signs of Discomfort: Signs of discomfort in dogs include vocalization, restlessness, reactivity, or aggression.  

1. Redness and Inflammation

Red eyes in dogs are telltale signs of conjunctivitis, leading to the condition’s nickname, “pink eye.”

Redness is the main inflammation effect, and eye redness develops when the conjunctival blood vessels become inflamed and swollen. 

The redness varies from light pink to striking red, depending on the severity of the inflammation. The discoloration is more pronounced in flat-faced dogs with bulging eyes. 

The conjunctiva returns to its standard color once the inflammation dissipates. 

2. Swelling and Puffiness

Swelling is the second of the five main inflammation signs. Swelling in dogs with conjunctivitis manifests with puffiness and is most intense on the eyelids. 

The eyelids appear the most swollen and puffy in the morning and after the dog wakes up from naps. Severe cases of conjunctivitis trigger excess swelling that shuts the eyelid completely. 

Wet compresses help relieve puffiness. Placing compresses on dogs is easier said than done, especially in hyperactive canines. 

3. Eye Discharge

Eye discharge in dogs with conjunctivitis develops due to increased secretion. The dog’s eye produces more liquid to wash away the irritation. 

The type of discharge reveals useful information about the cause of conjunctivitis. Thin and watery discharge points to viral infections, while thick and sticky discharge indicates bacterial presence.  

The discharge makes the eyes look messy and clumps unless cleaned, forming crusts around the dog’s eyes. 

4. Blinking and Squinting

Blinking and squinting are frequently reported in dogs with conjunctivitis and represent specific defense mechanisms.  

Blinking describes repetitive eyelid movement to remove the irritant, lubricate the eye, and restore vision. 

Squinting is staring through partially closed eyes. The medical term for squinting is blepharospasm. Squinting occurs to help the dog overcome photophobia or light sensitivity. 

5. Rubbing and Pawing

Rubbing and pawing are signs of eye itchiness, a common and anticipatory sign of dog conjunctivitis. 

The dog rubs and paws at their eyes to remove the source of irritation. The dog rubs with its paws or scratches against surfaces and fabric. Pawing refers to scratching with the paws specifically. 

Rubbing and pawing provide temporary relief but cause further damage to the eye. Pet owners must make their dogs wear an Elizabethan collar or E-collar to prevent additional eye injuries. 

6. Sensitivity to Light

Dog conjunctivitis causes light sensitivity. The clinical term for heightened sensitivity to light is photophobia. 

Dogs with photophobia squirm when exposed to bright light sources or environments and seek comfort in dim surroundings. 

Keep light settings low in the home during conjunctivitis treatment to help the dog relax. Dog goggles are a helpful tool for reducing light sensitivity during treatment.  

7. Increased Tear Production

Increased tear production refers to the overactivity of the tear glands. The medical term for the symptom is epiphora. 

Increased tearing gives the eyes a glassy appearance. Epiphora is a defense mechanism or the body’s effort to wash away the source of inflammation. 

“Acute conjunctivitis in dogs increases tear quantity” but “decreases tear quality,” according to a study on the “Impact of Acute Conjunctivitis on Ocular Surface Homeostasis in Dogs,” published in Veterinary Ophthalmology in 2020. 

8. Crust Formation

Crust formation is the clumping of eye discharge. Inflammation increases secretion and tearing of the eye. 

The discharge dries and clumps together when exposed to air,  forming crusts. Crust formation is noticeable in dogs with shaggy hair around the eyes. 

The crusts create an unkempt appearance and must be cleaned several times daily with a saline solution to prevent bacteria from proliferating around the dog’s eyes.  

9. Changes in Eye Appearance

Conjunctivitis affects the overall eye appearance. Common changes are redness, swelling, and excess discharge. 

The discharge is liquid, making the eye look teary or glassy or forming crusts. The crusts glue the eyelids and make eye movement unpleasant. 

The exact change depends on the dog conjunctivitis trigger and varies among dogs and breeds with different facial conformations. 

10. Signs of Discomfort

Dog conjunctivitis ranges from uncomfortable to painful, depending on the cause. Dogs display discomfort by behaving abnormally. 

Common signs of discomfort are loss of appetite, lethargy, sudden mood swings, and disinterest in everyday leisure activities. 

Incessant and abnormal vocalization, including crying, whining, and yelping, is a sign of discomfort in dogs with conjunctivitis. 

Dogs react abnormally when triggered by the pain and are usually more irritable and less friendly than normal. 

How is the Diagnosis of Conjunctiva in Dogs?

The diagnosis of conjunctivitis in dogs is complex. “One would think making a diagnosis of conjunctivitis and treating it appropriately would be one of the easiest things to face in general practice. However, this is a misconception for a number of reasons,” explains Christine Heinrich, author of the paper “Assessing Canine Conjunctivitis,” published in Vet Times in 2015. 

Dog conjunctivitis is challenging to diagnose as it occurs independently (primary) or as a symptom of another underlying health condition (secondary). 

The conjunctivitis symptoms and ocular changes are distinct, allowing the vet to determine the inflammation of the conjunctiva based on clinical appearance. 

The underlying cause of conjunctivitis requires in-depth analysis. The veterinarian conducts specialized ophthalmic tests and orders laboratory analysis to diagnose the cause. 

The owner's detailed history of the dog's condition aids the diagnostic process. Providing accurate information enables the veterinarian to distinguish between primary and secondary conjunctivitis.    

How are Dogs with Conjunctivitis Physically Examined?

Dogs with conjunctivitis are physically examined by inspecting the eye and testing the dog’s ocular reflexes. 

Inspecting the eyes entails scanning for growths, eyelid abnormalities, and pupil size issues. Commonly checked ocular reflexes include menace response, pupillary light reflex, and dazzle reflex. 

Dog conjunctivitis does not alter pupil size and ocular reflexes in otherwise healthy canines. 

How to Perform Eye Tests in Dogs with Conjunctivitis?

The eye tests to be performed on dogs with conjunctivitis are listed below. 

• Visual Inspection: Visual inspection refers to observing the eye and its main structures for abnormalities and function. The visual inspection is the first step of the ophthalmic examination and is an integral part of the physical assessment. 
• Ophthalmoscopy: Ophthalmoscopy is a specialized eye test in which the vet uses a direct ophthalmoscope to examine the eye’s deeper structures, including the bottom or fundus. Ophthalmoscopy is performed in a dark room, and the dog’s pupils must be dilated for accurate results. 
• Tonometry: Tonometry measures the dog’s intraocular pressure (IOP) using a handheld device called a tonometer. Dogs' normal eye pressure is between 20 and 28 mmHg, and values higher than 28 mmHg indicate glaucoma. 
• Schirmer Tear Test: The Schirmer tear test is used to diagnose dry eyes. The test involves placing a folded, hooked paper strip on the dog’s eyelid. The paper strip graduates (changes color), and tears start to wick up the paper once it is placed. The strip is left for one minute, after which the vet reads how many millimeters of tears the eyes produce. 
• Fluorescein Staining: Fluorescein staining is done to determine if there is an ulcer or damage to the cornea. The vet drops an orange stain into the dog’s eye. The stain turns fluorescent green and sticks to damaged parts of the cornea, where the epithelium is missing, giving a positive result. 
• Cytology: Conjunctival cytology helps identify different inflammatory cells and infectious organisms associated with dog conjunctivitis. Cytology is performed on conjunctival swabs or scrapings. 

Are there Laboratory Tests in Dogs with Conjunctivitis?

Yes, there are laboratory tests in dogs with conjunctivitis. Lab tests for dog conjunctivitis include bacterial cultures or sensitivity analysis, conjunctival cytology, conjunctival biopsy, PCR (polymerase chain reaction), CBC (complete blood count), and allergy testing. 

Bacterial cultures, PCR, and conjunctival cytology are tested using conjunctival swabs. A biopsy requires a tissue sample, CBC is determined through blood tests, and allergy testing is performed with intradermal, hair, saliva, or blood samples. 

What is the Treatment of Conjunctivitis in Dogs?

The treatment of conjunctivitis in dogs depends on the inflammation cause and includes topical medications, artificial tears, or surgery. 

Primary dog conjunctivitis is treated using topical antibiotics, anti-inflammatories, and steroids. The veterinarian prescribes the exact combination based on the bacteria or virus triggering the inflammation. 

Tear stimulants are recommended for dogs with conjunctivitis due to lack of tear production or dry eye. Eyelid defects and growths causing pink eye in dogs are treated surgically. 

Dogs with secondary conjunctivitis due to systemic conditions require a multimodal approach that targets the system disorder and manages eye inflammation symptoms. 

Is Home Remedy Helpful for Treating Conjunctivitis in Dogs?

Yes, a home remedy is helpful for treating conjunctivitis in dogs. Home remedies provide mild relief in dog conjunctivitis cases.  

Provide quick dog conjunctivitis relief at home by gently cleansing the eyes with a pet-friendly, vet-approved saline solution and applying a warm compress for several minutes.  

Use artificial tears to lubricate the eyes and place an Elizabethan collar on the dog to prevent it from pawing the itchy eyes, which worsens the condition. Ensure the environment is clean and free from irritants to speed up recovery. 

Daily CBD oil supplementation boosts the dog’s immune system, preventing infectious conjunctivitis. CBD lowers pain and inflammation, helping with conjunctivitis treatment. 

When is the Time to Visit a Veterinarian?

The time to visit a veterinarian for dog conjunctivitis is when the issue becomes apparent. Conjunctivitis is straightforward to treat in most cases, so visiting the vet promptly is essential for preventing progression and complications. 

What to do to Reduce the Risk of Conjunctivitis in Dogs?

Monitor for potential causes and learn how to prevent them to reduce the risk of conjunctivitis in dogs. 

Limit allergen exposure if the dog is sensitive to smoke, dust, or perfumes and suffers from allergy-related conjunctivitis. 

Close monitoring during playtime decreases the risk of trauma-induced dog conjunctivitis while staying up-to-date on vaccines prevents viral conjunctivitis caused by canine distemper, influenza, and herpes virus. 

Wipe the dog’s face and paws after being outside or in contact with other pets to maintain good hygiene. Wash the dog’s toys, bowls, and bedding regularly.