Why Are My Dog's Eyes Gunky? What Eye Discharge Actually Means

Almost every dog wakes up with a bit of gunk in the corner of the eye. You wipe it, it goes, that is the end of it.

The thing worth paying attention to is not whether there is discharge. It is whether it comes back. Tears are not just lubrication: they carry oxygen and nutrients to the surface of the eye and wash debris away. When something is wrong with the eye or with the tear film, the debris stops being washed away, and you find yourself wiping the same eye three times a day.

That is the signal. Here is how to read the rest of it.

What The Colour Usually Means

What you see	What it usually points to
A little grey or reddish crust, mornings only	Normal. Wipe it and move on
Clear and watery, running down the face	Irritation, allergy, wind, or a blocked tear duct
Clear but sticky and stringy	Early tear film problem, worth a check
Grey or white mucus that keeps returning	Classic dry eye. The mucus is what is left when the watery part of tears is missing
Yellow or green	Pus. Infection or an ulcer until a vet says otherwise
Reddish-brown staining down the fur	Usually porphyrins in tears, not blood. Cosmetic, but constant wetness has a cause
Actual blood	Same day. Always

Colour narrows it down. It does not diagnose it. Two conditions can look identical from the sofa and need opposite treatments, which is the whole reason the dye test exists.

The One Question That Narrows It Fastest

One eye, or both?

It is the first thing a vet will ask and it splits the possibilities almost in half.

One eye suggests something local. A grass seed, a scratch from a bramble or another dog, an ulcer, a blocked tear duct on that side. Something happened to that eye.

Both eyes suggests something affecting the whole dog. Allergies, an infection that has spread, or a tear production problem. Dry eye usually comes on gradually in both eyes over months.

Sudden onset in both eyes at once is the unusual one, and it is the pattern reported in the Years dog food recall. If that is what you are seeing and your dog has been eating a recalled food, say so when you ring.

When To Stop Reading And Ring The Vet

Go today, not next week, if you see any of these:

• The eye is being held shut, or the dog will not let you near it
• Obvious pain: rubbing on furniture, pawing hard, yelping when touched
• The surface looks cloudy, blue or hazy rather than clear
• The eye looks bigger, smaller, or is bulging
• Blood, or a discharge that is genuinely bloody rather than brown
• Your dog is bumping into things or seems unsure in dim light

Eyes deteriorate faster than most other things. A superficial ulcer that would have healed in days can become a deep one that threatens the eye, and the window is short.

The Usual Causes, Briefly

Allergies and irritants. Pollen, dust, smoke, shampoo. Usually both eyes, usually clear and watery, usually itchy elsewhere too.

Conjunctivitis. Inflammation of the pink tissue around the eye. Very common, often secondary to something else, which is why treating it without finding the cause tends to end with it coming back.

Dry eye, or keratoconjunctivitis sicca. The one most often missed, because it almost never looks dry. It looks gunky. If you have been wiping grey mucus off the same eye for weeks, read this one properly and ask for a Schirmer tear test by name.

A foreign body. Grass seeds are the classic, especially in summer and especially in spaniels. Sudden, one eye, and a dog that desperately wants to rub it.

Corneal ulcer. A break in the surface of the eye. Painful, urgent, and invisible without dye.

Blocked tear ducts. Tears that cannot drain spill down the face instead. More common in flat-faced breeds and in some small terriers.

Anatomy. Brachycephalic breeds have shallower sockets and eyelids that do not always close fully, so the surface dries and gets irritated. Some breeds have eyelids that roll inwards and rub. These are structural and they need a vet, not a wipe.

What The Vet Will Actually Do

Two tests do most of the work, and neither needs sedation.

Fluorescein stain. A green dye that clings to any break in the corneal surface and glows under blue light. This is how ulcers are found, and it changes the treatment plan completely, because an ulcer rules out steroids.

Schirmer tear test. A paper strip tucked inside the lower lid for 60 seconds, measuring how far the tears travel. Over 15mm a minute is normal. Our dry eye guide has the full scale and what each reading means.

If your dog has had a gunky eye for weeks and nobody has done either test, ask.

What Not To Do

Do not use leftover eye drops, and particularly not anything with a steroid in it. Steroid eye preparations get prescribed for all sorts of things and half-used tubes sit in drawers for years. If the cornea is ulcerated, a steroid slows healing and can let the ulcer deepen. You cannot tell whether there is an ulcer by looking at it.

Do not use another dog's medication. Same reasoning, plus you have no idea what is in it now.

Do not keep wiping and hoping past a few days. Wiping treats the symptom you can see. If it keeps coming back, something is producing it.

Do not leave a squinting eye overnight. Squinting means pain, and pain in an eye is not something dogs put up with for fun.

What It Costs

Item	Typical UK cost
Consultation	£40 to £70
Fluorescein stain	Usually included, or a few pounds
Schirmer tear test	Usually included, or a few pounds
Antibiotic drops	£15 to £30
Referral to an eye specialist, if needed	£150 to £300 for the first appointment

Prescription costs are worth knowing about separately, because you do not have to buy medication from the practice that prescribes it. We covered that in our guide to the vet prescription fee cap.

Floofers is not a veterinary practice and nothing here is a diagnosis. If your dog's eye is painful, cloudy, bloody or held shut, treat it as urgent and ring your vet.