A dog's eyes are remarkably expressive — and remarkably vulnerable. From the pink tissue blob that suddenly appears in the corner of a puppy's eye to the cloudy lens of a senior dog, eye problems in dogs range from cosmetically concerning to vision-threatening. Knowing the difference between conditions that need same-day emergency care versus those that can wait for a scheduled appointment could preserve your dog's sight.

This guide covers the most common eye conditions seen in general veterinary practice: cherry eye, cataracts, conjunctivitis, entropion and ectropion, dry eye (KCS), and corneal ulcers — along with clear guidance on urgency level for each.

Cherry Eye (Prolapsed Third Eyelid Gland)

That alarming pink or red blob in the inner corner of your dog's eye is not a tumor — it's a prolapsed gland of the third eyelid (nictitans gland). Dogs, unlike humans, have a third eyelid that contains a tear-producing gland anchored by connective tissue. When this anchor weakens, the gland pops out of position and becomes visible.

Cherry eye is common in young dogs and is particularly prevalent in Bulldogs, French Bulldogs, Beagles, Cocker Spaniels, and Shih Tzus. It is usually not painful, but the exposed gland dries out and becomes irritated, and it produces a significant portion of the eye's tear film — up to 30–40%.

Treatment: Surgical repositioning (tacking the gland back into place) is the treatment of choice. The outdated practice of simply removing the gland is now discouraged because it substantially increases the risk of dry eye (keratoconjunctivitis sicca, KCS) later in life. Success rates with repositioning surgery are high — around 90% — though some dogs require a repeat procedure. Most vets recommend treating cherry eye promptly rather than waiting, to minimize chronic irritation and gland damage.

Urgency level: Schedule within a week or two — not an emergency, but don't delay indefinitely.

Cataracts

A cataract is an opacity of the lens — the normally clear structure behind the iris that focuses light onto the retina. Cataracts range from small incidental opacities that don't affect vision to complete lens opacity causing blindness.

Causes include:

• Hereditary cataracts: The most common cause in dogs. Many breeds carry genes for early-onset cataracts, including Poodles, Cocker Spaniels, Golden Retrievers, Labrador Retrievers, Boston Terriers, and Siberian Huskies.
• Diabetic cataracts: Dogs with diabetes mellitus develop cataracts extremely rapidly — often within months of diabetes onset — due to altered glucose metabolism in the lens. This is the second most common cause.
• Age-related (senile) cataracts: Common in dogs over 9–10 years old; may not significantly impair vision.
• Secondary cataracts: Following uveitis (inflammation inside the eye), retinal degeneration, or trauma.

Don't confuse cataracts with nuclear sclerosis — a normal aging change that makes the lens appear slightly hazy or blue-grey but does not significantly impair vision. A veterinary eye exam can reliably distinguish the two.

Treatment: The only effective treatment for vision-impairing cataracts is surgical phacoemulsification (cataract surgery), performed by a board-certified veterinary ophthalmologist. Success rates are excellent (over 90%) when surgery is performed before secondary complications develop. The AVMA recommends early referral to an ophthalmologist when cataracts are identified.

Urgency level: Schedule an ophthalmology consultation within weeks. Cataracts left untreated can cause secondary glaucoma or lens-induced uveitis, which may eliminate surgery as an option.

Conjunctivitis

Conjunctivitis — inflammation of the pink mucous membrane lining the eyelids and covering the white of the eye — is the most common eye condition seen in dogs. It presents as redness, discharge (clear, yellow, or green), swelling, and frequent blinking or pawing at the eye.

Causes range from environmental irritants (dust, smoke, plant material), allergies, and viral or bacterial infections to secondary signs of systemic disease or anatomical problems. In dogs, primary bacterial conjunctivitis is less common than in cats — discharge is more often secondary to another problem.

Treatment: Depends entirely on the cause. Your vet will examine the eye thoroughly (including checking intraocular pressure to rule out glaucoma) before prescribing topical antibiotics, anti-inflammatory drops, or allergy management. Never use leftover human eye drops or medicated drops from a previous prescription without veterinary guidance — some human formulations are toxic to dogs, and steroid drops applied to an undiagnosed corneal ulcer can cause catastrophic progression.

Dry Eye (Keratoconjunctivitis Sicca / KCS)

KCS occurs when the lacrimal glands fail to produce adequate tear film. Without sufficient tears, the corneal surface becomes dry, irritated, and prone to infection and ulceration. It is common in Bulldogs, West Highland White Terriers, Cocker Spaniels, Shih Tzus, and Lhasa Apsos.

Signs include persistent thick, mucoid discharge (the eye produces mucus to compensate for missing aqueous tears), redness, dullness of the corneal surface, and progressive corneal scarring (pigmentation) that can impair vision.

Diagnosis is simple: a Schirmer tear test measures tear production in 60 seconds. Values below 15 mm/min are abnormal; below 10 mm/min is severe KCS.

Treatment with cyclosporine ophthalmic ointment (Optimmune) or tacrolimus stimulates natural tear production in most dogs — often dramatically. Treatment is lifelong but highly effective. Visit VCA Hospitals for a thorough overview of KCS management options.

Corneal Ulcers

A corneal ulcer is a break in the surface epithelium of the cornea. It can result from trauma (a scratch from a cat, a plant, or vigorous rubbing), foreign bodies, KCS, entropion (inward-rolling eyelids), or infection. Signs include squinting, tearing, redness, and apparent pain (the cornea is extremely sensitive).

This is an urgent condition. Corneal ulcers can progress rapidly to deep ulcers (descemetoceles) or perforation within 24–48 hours, particularly if the dog rubs the eye. An E-collar (cone) must be worn to prevent self-trauma until healing is confirmed.

Diagnosis requires fluorescein stain — a green dye that adheres to areas where the corneal surface is absent. Treatment typically includes topical antibiotic drops, pain management, and frequent rechecks until healing is confirmed. Deep or non-healing ulcers may require surgical intervention.

Glaucoma — The Silent Emergency

Glaucoma is elevated intraocular pressure that damages the optic nerve. It can be primary (inherited) or secondary (following uveitis, lens luxation, or other conditions). Acute glaucoma is exquisitely painful and can cause permanent blindness within 24–72 hours.

Signs: a red, painful eye; a fixed, dilated pupil; cloudiness of the cornea; apparent headache behavior (reluctance to move the head). If you suspect glaucoma, this is a same-day emergency. Breeds at risk for primary glaucoma include Basset Hounds, Beagles, Cocker Spaniels, Chow Chows, and Siberian Huskies.

When to See the Vet: A Practical Urgency Guide

• Same-day/emergency: Sudden vision loss, squinting with apparent pain, red eye with pupil abnormality (suggesting glaucoma), bulging or sunken eye, visible eye trauma, green or yellow discharge with pain.
• Within 48–72 hours: Any discharge that doesn't resolve in 24 hours, persistent redness, first appearance of cloudiness in the lens.
• Within 1–2 weeks: Cherry eye (no pain), gradually worsening cataracts, mild intermittent discharge without other signs.
• Annual wellness exam: Routine eye screening for breeds predisposed to hereditary conditions.