Normal Versus Abnormal Eye Discharge in Dogs
A small amount of discharge from your dog's eyes is entirely normal. The eye continuously produces tears to lubricate its surface, and this fluid, along with small amounts of mucus and cellular debris, drains via the nasolacrimal (tear) duct into the nasal cavity. When this drainage is temporarily disrupted — after sleep, for example — a small amount of dried crust may accumulate at the inner corner of the eye. This is the canine equivalent of sleep in the corner of a human eye, and in most cases it can be gently wiped away with a damp cotton wool pad.
Discharge becomes a concern when it is persistent, copious, changes in character, is associated with other eye changes such as redness or cloudiness, or causes your dog obvious discomfort. Understanding the type of discharge present is the first step in identifying the underlying cause.
Types of Eye Discharge and What They Suggest
Clear, Watery Discharge
Thin, clear, watery discharge (epiphora) can result from increased tear production or impaired drainage. Common causes include allergies (environmental or food), irritation from dust, wind or foreign material, blocked nasolacrimal ducts, and certain anatomical conformations — notably in brachycephalic (flat-faced) breeds such as Pugs, French Bulldogs, and Shih Tzus whose shallow eye sockets and facial skin folds impair normal drainage. In most cases, clear watery discharge alone is not immediately alarming, but persistent cases warrant a veterinary check.
White or Grey Mucoid Discharge
Thick, white or grey mucus — similar in appearance to raw egg white — is often associated with keratoconjunctivitis sicca (KCS), also known as dry eye. In KCS, the tear glands produce insufficient aqueous (watery) tears, leaving the eye poorly lubricated. The eye compensates by overproducing mucus. This chronic condition causes significant discomfort and, if left untreated, can lead to corneal scarring and blindness. KCS is common in West Highland White Terriers, Cavalier King Charles Spaniels, Yorkshire Terriers, and English Bulldogs.
Yellow or Green Discharge
Yellow or green purulent (pus-like) discharge indicates a bacterial infection of the eye or its surrounding structures. This type of discharge is almost always abnormal and requires prompt veterinary assessment. Sources include bacterial conjunctivitis (particularly if both eyes are involved), infected corneal ulcers, and dacryocystitis (infection of the nasolacrimal duct). Do not attempt to treat purulent eye discharge at home without veterinary guidance — appropriate antibiotic selection depends on which organism is involved.
Bloody Discharge
Blood-tinged discharge from the eye is always a reason to seek urgent veterinary attention. Causes include trauma, severe conjunctivitis, uveal disease, and — most urgently — glaucoma, a condition involving elevated pressure within the eyeball that can cause permanent blindness within hours if untreated.
Common Causes of Abnormal Eye Discharge
Conjunctivitis
Inflammation of the conjunctiva — the pink tissue lining the inner surface of the eyelids and the white of the eye — is the most common cause of abnormal eye discharge in dogs. It can be caused by bacteria, viruses, allergens, irritants, or be secondary to another eye condition. Symptoms include redness, discharge (ranging from clear to purulent), and squinting. Both eyes are often affected in allergic or viral cases; bacterial conjunctivitis may be unilateral initially.
Keratoconjunctivitis Sicca (Dry Eye)
As described above, KCS results from inadequate aqueous tear production, most commonly due to immune-mediated destruction of the lacrimal glands. It is diagnosed using the Schirmer Tear Test — a standardised strip of filter paper placed at the inner corner of the lower eyelid for exactly 60 seconds measures tear production in millimetres. A value below 10 mm/min strongly indicates KCS; below 5 mm/min is severe. Treatment typically involves immunosuppressive eye drops (cyclosporine or tacrolimus) to restore tear production, along with regular artificial tear supplementation.
Entropion
Entropion is an inward rolling of the eyelid margin, causing the eyelid hairs and skin to rub continuously against the corneal surface. This produces intense irritation, increased tear production, and eventually corneal ulceration. It is particularly common in Chow Chows, Shar-Peis, Labrador Retrievers, Golden Retrievers, and Rottweilers. Surgical correction is the definitive treatment.
Corneal Ulceration
A corneal ulcer is a defect in the surface of the cornea that can range from superficial to full-thickness (perforating). Any condition causing surface irritation — foreign bodies, entropion, dry eye, trauma — can lead to ulceration. Signs include marked squinting (blepharospasm), tearing, and sometimes a visible cloudy or blue-white patch on the corneal surface. Corneal ulcers require prompt treatment and must not be treated with steroid-containing eye drops, as steroids impair corneal healing and can worsen ulceration dramatically.
Glaucoma
Glaucoma is an increase in intraocular pressure (IOP) that damages the optic nerve and retina, leading to permanent vision loss. Acute glaucoma is an ophthalmic emergency — affected dogs display a suddenly red, painful eye, cloudiness of the cornea, and a fixed, dilated pupil. The eye may appear visibly enlarged. Without emergency intervention (intravenous mannitol, topical medications to reduce IOP, and often surgery), blindness can occur within 24–48 hours. Breeds predisposed include Basset Hounds, Cocker Spaniels, Dalmatians, and Beagles.
When to See a Vet Urgently
Seek immediate veterinary attention if your dog shows any of the following:
- A suddenly red, very painful, or cloudy eye
- Visible squinting (keeping the eye partially or fully closed)
- A visible abnormality of the cornea — cloudiness, blue tinge, or a white spot
- Bloody discharge
- A visibly enlarged eye
- Sudden changes in vision — bumping into objects or reluctance to navigate familiar spaces
Home Care Dos and Don'ts
While awaiting a vet appointment for mild cases, the following home care measures are appropriate:
- Do: Gently clean away discharge using a damp cotton wool pad, wiping from the inner corner outward. Use a fresh piece of cotton wool for each eye to prevent cross-contamination.
- Do: Use sterile saline drops (available from pharmacies) to flush mild irritants from the eye surface if advised by a vet.
- Don't: Use human eye drops — many contain preservatives or active ingredients that are toxic to dogs.
- Don't: Apply any steroid-containing preparation unless specifically prescribed for confirmed non-ulcerative disease.
- Don't: Delay seeking veterinary care if symptoms worsen, the dog is clearly in pain, or any of the urgent signs above are present.
For gentle eye wipes and saline rinse solutions formulated specifically for dogs, Zooplus stocks a range of veterinary-grade eye care products suitable for regular maintenance of breeds prone to discharge and tear staining.