Cat third eyelid showing: what it means
The third eyelid, or haw, is a pale membrane that sweeps across a cat's eye from the inner corner. In a healthy, awake cat it should barely be visible, so a haw you can plainly see is a sign worth acting on. Showing in both eyes usually points to a general problem such as illness, weight loss, dehydration, gut upset, or pain. Showing in one eye more often means a local eye problem such as a scratch, ulcer, foreign body, or infection, and any painful eye with squinting needs a vet promptly, because corneal ulcers can worsen within a day.
This page is general pet health information, not a diagnosis or treatment plan for your pet. Always confirm anything urgent with a licensed veterinarian.
When to see a vet today
See a vet today if you notice One eye with a visible haw plus squinting, tearing, or pawing at the face, A cloudy, blue, or white area on the surface of the eye, and A haw showing in both eyes with lethargy, not eating, vomiting, or diarrhea. These are the signs that should not wait for home care or a watch-and-see approach. If any of them appear, skip the rest of this guide and call your vet or an emergency clinic now - waiting is the risky option.
- ●One eye with a visible haw plus squinting, tearing, or pawing at the face
- ●A cloudy, blue, or white area on the surface of the eye
- ●A haw showing in both eyes with lethargy, not eating, vomiting, or diarrhea
- ●The eye looks sunken or the cat is dehydrated and off food
- ●Uneven pupil sizes, drooping eyelid, or a sunken eye on one side
- ●Any coloured discharge, swelling, or a bulging eye
Safe to monitor at home
Milder signs are usually safe to watch for a day or two: A brief flick of the haw as your cat wakes from sleep, then a normal eye, Both eyes fully open, clear, and comfortable when your cat is alert, and Normal appetite, normal energy, and stable weight. Keep notes and photos so you can spot a trend. Anything that worsens, spreads, or comes with appetite, energy or behavior changes moves out of this category and into a vet visit.
- ●A brief flick of the haw as your cat wakes from sleep, then a normal eye
- ●Both eyes fully open, clear, and comfortable when your cat is alert
- ●Normal appetite, normal energy, and stable weight
What to photograph or record
Photograph or record Photograph both eyes straight on in daylight, without flash, Take a close up of the affected eye filling the frame, and Note whether the haw is in one eye or both, and how long it has been there in good, even light. Clear, well-framed evidence is what lets a vet - or a PetLumen scan - judge the change instead of guessing from a description. The checklist below is the exact shot list.
- Photograph both eyes straight on in daylight, without flash
- Take a close up of the affected eye filling the frame
- Note whether the haw is in one eye or both, and how long it has been there
- Photograph the pupils in the same lighting to compare their sizes
- Weigh your cat and note any recent diarrhea, vomiting, or reduced appetite
Likely causes
The causes vets consider first for this presentation are corneal ulcer or scratch, conjunctivitis and cat flu, illness, dehydration, or weight loss, and haw syndrome. Most are manageable once identified, but they look similar from the outside, which is why a photo-based triage and, when needed, an exam matter more than guesswork.
Corneal ulcer or scratch
A painful surface injury in one eye makes the haw come across protectively, with squinting and tearing. It needs staining by a vet, and steroid drops can make it much worse.
Conjunctivitis and cat flu
Feline herpesvirus and other infections inflame both eyes, producing discharge, sneezing, and visible haws, often flaring at times of stress.
Illness, dehydration, or weight loss
Loss of the fat pad behind the eye lets it sit slightly further back, so the haw shows. It is a general marker that a cat is unwell rather than an eye disease itself.
Haw syndrome
Both haws protrude, usually in a young cat with recent diarrhea, and the cat is otherwise bright. It typically resolves over weeks, but a vet should confirm it first.
Horner's syndrome
Nerve disruption on one side gives a protruding haw with a droopy lid, a small pupil, and a sunken eye. It follows ear disease, injury, or a chest problem.
Pain elsewhere
Cats in pain from any cause often show the haw, so a persistently visible membrane in a cat that also hides or eats less is a reason for a full examination.
Safe home care
For mild cases, safe home care is do not touch, wipe, or attempt to push the third eyelid back, wipe only discharge on the surrounding fur, using cooled boiled water and a fresh pad per eye, and never use human eye drops or leftover drops prescribed for another pet. These steps comfort and monitor; they do not treat the underlying cause. Stop home care and call a vet if anything in the urgent list above appears or the trend moves the wrong way.
- -Do not touch, wipe, or attempt to push the third eyelid back
- -Wipe only discharge on the surrounding fur, using cooled boiled water and a fresh pad per eye
- -Never use human eye drops or leftover drops prescribed for another pet
- -Keep your cat indoors and away from dust and draughts until seen
- -Encourage water and offer warmed wet food if appetite is reduced
- -Book a vet appointment for any haw that persists beyond a day, or any painful eye today
PetLumen is a triage and monitoring tool, not a substitute for veterinary care. Always confirm treatment plans with a licensed veterinarian.
Frequently asked
Is a visible third eyelid ever normal in a cat?
A momentary flick as a cat wakes or blinks is normal, but a haw you can clearly see in an alert cat is not. It is one of the more reliable outward signs that something is wrong, and cats hide illness well otherwise. Because it can accompany anything from a scratched cornea to significant weight loss, it should prompt a look at the whole cat, not just the eye.
Does one eye versus both eyes change what it means?
It is the most useful distinction you can make at home. One haw usually indicates a local problem in that eye, such as an ulcer, foreign body, or nerve issue, and is often painful. Both haws more often reflect a whole body cause, including dehydration, weight loss, gut upset, or haw syndrome. Note which pattern you see and tell your vet when you book.
Can I push the third eyelid back myself?
No. The membrane is delicate, the eye may already have a painful ulcer you cannot see, and pressure risks worsening it. Handling also stresses a cat that is already unwell. Limit yourself to gently wiping discharge from the surrounding fur and to taking clear photographs, then let a vet examine the eye and stain it to check for surface damage.
What is haw syndrome?
It is a recognised condition in which both third eyelids protrude, typically in younger cats, often after a bout of diarrhea, while the cat remains bright and eating. It usually settles over several weeks without specific treatment. It is nevertheless a diagnosis made by a vet after excluding painful eye disease and systemic illness, so it should not be assumed at home.
What should I bring to the appointment?
Daylight photographs of both eyes straight on, a close up of the affected side, a note of when it started and whether one or both eyes are involved, your cat's current weight, and any recent diarrhea, vomiting, or appetite change. PetLumen's eye scan mode helps you capture a focused, well lit image and keeps it dated on the timeline, but it does not replace the stain test a vet will run.
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