Close-up of a dog's face showing its eyes
on September 17, 2026

Dog Eye Infection: Causes, Symptoms & When It's Serious (UK Guide)

A red or weepy eye in a dog can mean something as minor as a bit of dust, or it can be an emergency that risks permanent damage within days if it's missed. Telling the difference matters, and it isn't always obvious just from looking. This guide covers the real causes of dog eye infections, how to spot the warning signs that separate simple irritation from something urgent, and exactly when a red eye needs a same-day vet visit rather than a wait-and-see approach.

Written by Jamie Sinclair, who writes about canine health, nutrition, and everyday care for Doggy Dailies — focused on translating veterinary research and real ingredient science into practical, honest guidance UK dog owners can use.

Close-up of a dog's face showing its eyes

Table of Contents

What Causes Eye Problems in Dogs

Most red, weepy or swollen eyes in dogs come down to conjunctivitis — inflammation of the pink membrane lining the eye and eyelid — but conjunctivitis itself isn't one single problem. It's a symptom with a long list of possible causes: bacterial or viral infection, allergies, environmental irritants like dust, pollen or smoke, dry eye (a lack of adequate tear production), eyelid abnormalities that cause lashes or fur to rub against the eye, a foreign object such as a grass seed lodged behind the third eyelid, or an underlying eye injury like a corneal ulcer. This is exactly why "eye infection" isn't always the right label — sometimes it's genuinely infectious, and sometimes the redness is a knock-on effect of something else entirely, which changes what treatment actually works.

Symptoms to Look For

  • Redness or a bloodshot appearance in the white of the eye
  • Weeping, discharge, or crusting around the eye — clear, yellow or green discharge can all occur depending on the cause
  • Swelling of the eyelid or the area around the eye
  • Squinting, holding the eye partly or fully closed
  • Excessive blinking or pawing/rubbing at the face
  • Cloudiness or a visible change to the surface of the eye
  • Sensitivity to light

A dog with mild, short-lived redness and a bit of clear discharge, who is otherwise bright and not pawing at the eye, is usually dealing with something minor like dust or pollen. The pattern that should raise concern is different, and it's covered next.

Conjunctivitis vs Something More Serious: Why the Distinction Matters

This is the part most owners aren't told clearly enough. Conjunctivitis — inflammation of the surface membrane — is genuinely one of the more manageable eye problems a dog can have, and plenty of cases clear up with simple treatment once the cause is identified. A corneal ulcer is a different and much more urgent problem: it's a break in the surface of the cornea itself, the clear window at the front of the eye, and it can progress from minor irritation to a ruptured eye within days if left untreated. The two can look confusingly similar in the first day — both cause redness, squinting and discharge — which is exactly why a vet check is the right call whenever you can't be confident it's simple conjunctivitis.

A few signs point more specifically toward a corneal ulcer or another urgent problem rather than straightforward conjunctivitis: a dog holding the eye tightly shut rather than just blinking more than usual, visible cloudiness or a change in the normal clear surface of the eye, sudden and severe pain (pawing at the face, reluctance to be touched near the eye), a history of recent trauma (a stick, a scratch, rough play with another dog), or any sign that the eye itself looks physically different in shape or surface rather than just red and weepy around the edges. None of these are things to diagnose confidently at home — the point of knowing them is recognising when "wait and see" isn't the safe option, not making the call yourself.

The Real Numbers Behind Corneal Ulcers

It's worth knowing just how common corneal ulcers actually are, and how sharply the risk varies by breed, because the numbers back up why urgency matters so much for some dogs more than others. A large VetCompass study from the Royal Veterinary College, analysing primary veterinary care records for over 100,000 dogs across England, found that almost 1 in every 100 dogs will be affected by a corneal ulcer in any given year. That makes it a genuinely common problem, not a rare complication — and the risk isn't spread evenly across all dogs.

Flat-faced (brachycephalic) breeds carried over 11 times the risk of corneal ulcers compared with non-brachycephalic breeds in the same study, and Pugs specifically stood out even within that group, with over 19 times the risk compared with crossbred dogs. Purebred dogs in general had more than twice the risk of crossbreds, and Spaniel breeds — often prone to eyelid conformation issues — showed over 3 times the risk of non-spaniel breeds. If you own one of these breeds, this isn't a theoretical concern; it's a measurable, well-documented pattern.

The study also makes clear that corneal ulcers aren't a minor inconvenience when they do happen. Nearly 60% of affected dogs needed pain relief, roughly 1 in 5 needed surgery, and the condition contributed to death in more than 1 in 10 of the affected dogs that died during the study period. That's exactly why the urgency signs covered above matter so much — for a Pug, a French Bulldog, or a Spaniel with a suddenly squinty or cloudy eye, "wait and see" carries a real cost, backed by data from over 100,000 dogs rather than guesswork.

Common Causes, Explained

  • Allergies — seasonal or environmental allergens can inflame the eye area just as they inflame skin, often alongside other allergy signs like itchy paws or ears
  • Environmental irritants — dust, smoke, sand, or even shampoo residue can cause temporary irritation that settles once the irritant is gone
  • Dry eye (keratoconjunctivitis sicca) — a chronic lack of adequate tear production, which needs ongoing veterinary management rather than a one-off treatment
  • Foreign objects — grass seeds are a particularly common UK problem in the warmer months, often lodging behind the third eyelid where they're not obvious without a vet's examination
  • Eyelid abnormalities — conditions like entropion (where the eyelid rolls inward) cause chronic rubbing and irritation, and are more common in certain breeds
  • Bacterial or viral infection — can occur on its own or develop secondarily once the eye's surface is already irritated or damaged

Breeds More Prone to Eye Problems

Brachycephalic (flat-faced) breeds — Pugs, French Bulldogs, English Bulldogs, Shih Tzus, and similar breeds with shallow eye sockets and prominent, protruding eyes — are more prone to eye injuries and corneal ulcers simply because their eyes sit more exposed and are more easily scratched or knocked. Breeds prone to entropion, such as Chow Chows, Shar Peis, and some Spaniel breeds, are also at higher risk of chronic irritation from their own eyelids and lashes rubbing against the eye's surface. This doesn't mean other breeds are immune — any dog can develop conjunctivitis or pick up a grass seed — but if you own one of these breeds, it's worth knowing your dog carries a higher baseline risk and treating any eye symptom with a bit more urgency.

What You Can Do at Home

For mild, clearly minor irritation — a bit of dust after a walk, some clear discharge with no other symptoms — gently wiping around (not on) the eye with a clean, damp cotton pad, wiping outward away from the tear duct, can help. Never apply any human eye drops, ointments, or home remedies directly into a dog's eye without veterinary guidance — some common human treatments are actively harmful to a dog's eye, and using the wrong drops on an undiagnosed ulcer can make things significantly worse. If your dog is pawing at the eye, an Elizabethan collar or similar protective cone can prevent them from causing further damage to an already irritated or injured eye while you get them seen.

Treatment Your Vet May Use

Treatment depends entirely on the actual cause, which is exactly why a proper examination matters rather than guessing from home. For infectious or inflammatory conjunctivitis, antibiotic or anti-inflammatory eye drops are common, often needing to be applied several times a day for a week or more. Corneal ulcers typically need more intensive treatment — antibiotic drops given as often as every few hours in some cases, pain relief, and sometimes medication to prevent the eye's own healing response from causing further damage. A protective cone is almost always part of ulcer treatment, since a dog rubbing at a healing ulcer can undo days of progress in seconds. Severe or non-healing ulcers may need referral to a veterinary ophthalmologist and, in some cases, surgery. Foreign objects like grass seeds usually need to be located and removed under sedation, since they can be lodged somewhere not visible on a simple look.

When to See a Vet

  • Any eye held shut, or squinting that doesn't improve within a few hours
  • Visible cloudiness, a change in the eye's surface, or anything that looks physically different about the eye itself
  • Sudden, severe discomfort — persistent pawing at the face, reluctance to be touched near the eye
  • Yellow or green discharge, rather than clear
  • Any known recent injury to the eye, even if it looks minor at first
  • Symptoms that don't improve, or that worsen, within 24-48 hours
  • Any eye symptom in a brachycephalic breed, given their higher baseline risk of serious complications

When in doubt, treat a red or painful eye as something to get checked rather than something to watch — the cost of a wasted vet visit is far lower than the cost of a missed corneal ulcer.

Preventing Future Eye Problems

Keeping the hair around a long-coated dog's eyes trimmed can reduce irritation from fur rubbing against the surface. During grass seed season (roughly late spring through summer in the UK), checking your dog's eyes, ears and paws after walks through long grass catches problems early, before a lodged seed has time to cause real damage. If your dog has a known allergy pattern, managing that allergy more broadly — including diet, as covered in our guide to food for dogs with allergies — can reduce how often eye symptoms flare up alongside skin and ear symptoms. If your dog's eye problems tend to come alongside paw issues, our guide to dog paw infections covers a similar cause-and-treatment pattern worth knowing.

FAQ

How do I know if my dog's eye infection is serious?

Watch for an eye held shut, cloudiness or a visible change to the eye's surface, severe pain, or discharge that's yellow or green rather than clear. Any of these warrant a same-day vet visit rather than waiting.

Can I use human eye drops on my dog?

No. Never use human eye drops, ointments or home remedies in a dog's eye without veterinary guidance — some can actively worsen an underlying problem like a corneal ulcer.

What's the difference between conjunctivitis and a corneal ulcer in dogs?

Conjunctivitis is inflammation of the eye's surface membrane and is usually manageable. A corneal ulcer is a break in the cornea itself and can progress to serious damage within days, so it needs prompt veterinary treatment.

Are some dog breeds more prone to eye infections?

Yes. Brachycephalic breeds like Pugs, French Bulldogs and Shih Tzus have shallow eye sockets and prominent eyes, making them more prone to injury and ulcers. Breeds prone to entropion, like Chow Chows and Shar Peis, are more prone to chronic irritation.

Why does my dog keep getting eye infections?

Recurring eye symptoms are worth a proper vet investigation rather than repeat home treatment, since an underlying cause — allergies, dry eye, an eyelid abnormality, or a chronic irritant — is often driving the pattern and needs addressing directly rather than treating each flare-up in isolation.

Sources

This article is for general information only and isn't a substitute for veterinary advice. If your dog's eye looks painful, cloudy, or held shut, please contact your vet promptly.

Related: More on Skin & Coat Care