What this means
In the morning there is sometimes some dried mucus or a few brownish crumbs in the corner of the eye. That does not mean illness. Yellowish, greenish, thick or copious discharge is different, especially if it builds up through the day and the eye is red or stuck shut.
Pus-like discharge is not a diagnosis but a sign that something is going on in the eye: inflammation, dryness, irritation, a foreign body, a problem with the shape of the eyelid, or changes to the third eyelid. When it comes from one eye, especially if your dog squints, the cause is more likely local. When it comes from both eyes together with coughing, sneezing or lethargy, it may be a more general illness.
Look at the colour and thickness of the discharge, whether it is from one eye or both, whether the eye is red, whether your dog squints, and whether you can see a red lump in the corner of the eye. Photograph the eye. Do not clean it with unusual products or put in anything you chose yourself, as that could do harm.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your dog.
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Inflammation of the eye's lining
The eye reddens and waters, mucus or pus collects, and the lids may stick together. It is one possible cause, but the name alone does not say why the inflammation has happened.
About the condition: Conjunctivitis -
Dry eye
When too few tears are made the surface of the eye dries out and produces thick, yellow or stringy discharge. The eye surface may look dull.
About the condition: Dry eye (keratoconjunctivitis sicca) -
An eyelid turned inwards or other lid problems
A lid or lashes rubbing on the eye's surface irritate it. Discharge, watering and squinting follow.
About the condition: Entropion -
A red lump in the corner of the eye
A prolapsed gland of the third eyelid looks like a red or pink lump in the corner of the eye, and can irritate it and cause discharge.
About the condition: Cherry eye -
A foreign body or injury
A seed, grit or a scratch causes discharge to appear suddenly, usually from one eye, with squinting.
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A more general infection or inflammation
Sometimes discharge from both eyes is part of a general illness: nasal discharge, coughing or weakness may come with it.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- Colour and thickness of the discharge: clear, mucus, yellow, green
- Whether it is from one eye or both
- Whether the lids are stuck together, especially on waking
- Whether the eye is red, or your dog squints or rubs it
- Whether a red lump is visible in the corner of the eye
- Whether there is also nasal discharge, coughing or reduced appetite
When to book a routine visit
Book a visit if the eye is discharging or the discharge does not stop within a day or two, if the eye is red or your dog squints, if you can see a red lump in the corner, or if the discharge keeps coming back. Do not use drops or ointments prescribed at another time or for another animal.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- Dry eye (keratoconjunctivitis sicca) Eyes Dry eye is a condition in which the tear glands make too few tears, so the cornea and the conjunctiva dry out and become inflamed. Without its protective tear film the eye becomes sore, and over time the cornea can darken, scar and lose its clarity. This can weaken eyesight, so changes are worth showing to a vet.
- Eye problems Eyes A dog's eyes can be affected by many different problems: faults of the eyelids and lashes, inflammation, injuries, corneal ulcers, clouding of the lens or diseases of the retina. Eyes are sensitive and some kinds of damage can get worse quickly and affect sight, so changes in the eyes are not something to wait out. If an eye suddenly turns red, seems painful or has been injured, the dog needs to see a vet immediately.
- Entropion Eyes Entropion is a condition in which the edge of the eyelid rolls inwards, so the eyelashes and eyelid hair rub against the surface of the eye. The constant rubbing irritates and hurts the eye and can damage the cornea, leading to ulcers. It can be inherited and show up in young dogs, and it sometimes develops later because of other changes to the eye or eyelids.
- Cherry eye Eyes This is a condition in which the tear gland of the third eyelid slips out of place and bulges from the inner corner of the eye as a red lump that looks like a cherry. The gland produces part of the tears, so if it stays out for long it can dry out, swell and keep the eye less moist. Although it looks alarming, it is not a major source of pain, but the eye is worth showing to a vet.
- Distemper Infections Distemper is a contagious viral disease that can damage the airways, the digestive system, the skin and the nervous system. Puppies and unvaccinated dogs are at greatest risk. What is making a dog ill and how far the disease has gone is for a vet to work out, and the first signs are easily mistaken for an ordinary cold.
- Conjunctivitis Eyes Conjunctivitis is inflammation of the conjunctiva, the thin pink membrane that lines the inside of the eyelids and covers the white of the eye. It can be caused by dust and other irritants, allergy, infection, dry eye or faults of the eyelids or lashes, and sometimes it is part of a general illness; what caused the inflammation is for a vet to work out.
Body systems: Eyes Infections