What this means
Squinting is the dog's way of protecting the eye. When the eye hurts or is irritated, the muscles of the lid contract and the eye closes or half closes. When only one eye squints, the cause is usually in that eye: damage to the cornea, a foreign body, inflammation or raised pressure.
Eyes are delicate, and some problems, such as a corneal ulcer or raised eye pressure, can damage sight within hours or days. So you should not wait just because your dog is still eating and playing.
Note when the squinting began, whether the eye is watering, red, cloudy or has discharge, and whether your dog rubs the eye with a paw. Photograph the eye in good light. Do not put in any drops, and do not try to take something out of the eye 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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Corneal damage or ulcer
A scratched or damaged front surface of the eye is very painful. The dog shuts the eye, it waters, and it may look cloudy or have a dent.
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A foreign body or irritant
A speck, a bit of plant or a hair under the lid causes sudden squinting and watering, usually from one eye.
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Eyelid or lash problems
A lid rolled inwards or extra lashes scrape the surface of the eye and cause constant irritation and squinting.
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Raised pressure inside the eye
When pressure in the eye rises it hurts and reddens, the pupil may widen, and vision can fail quickly. This is an urgent condition.
About the condition: Glaucoma -
Eye inflammation
An inflamed eye is painful, red, sensitive to light, with discharge or tears.
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Changes in the cornea
Some corneal disorders cause cloudiness, discomfort or sometimes pain and squinting. Only a vet can assess them.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- When the squinting began, and whether it came on suddenly
- Whether the eye is watering, red or has discharge
- Whether the eye surface is cloudy, bluish or shows a dent
- Whether your dog rubs the eye with a paw or the face on the carpet
- Whether the pupils are the same size
- Whether your dog avoids light or seems low
When to book a routine visit
Contact a vet the same or the next day if your dog squints one eye. Do not wait for it to pass. Say when it began and whether there was a blow or contact with anything irritating. Do not use any drops you have at home without asking a vet.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- 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.
- Glaucoma Eyes Glaucoma is a condition in which the pressure inside the eye rises because fluid can no longer drain out of the eye as it should. The raised pressure presses on the retina and the optic nerve, so glaucoma is very painful and can quickly take away sight. It is an emergency: the dog needs 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.
- Distichiasis Eyes Distichiasis is a condition in which extra eyelashes grow from the edge of the eyelid, where no lashes should be. Soft lashes may barely bother the eye, but stiffer ones rub against its surface. Constant rubbing irritates the eye and can damage the cornea, so whether the lashes are causing harm is for a vet to judge.
- Corneal dystrophy Eyes Corneal dystrophy is an inherited condition in which fat or mineral deposits build up in the clear cornea of the eye, or its cells stop working properly, so the cornea becomes cloudy in places. It can be entirely painless and affect vision little, but some forms can cause the cornea to swell or develop small ulcers. A vet assesses the changes and follows how they develop.
- 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