Haws syndrome – the third eyelid is showing.

Haws_3 Cats and dogs have a third eyelid.   Normally you don’t see it, as it stays tucked down in the corner of the eye.  There are tear-producing glands on the back side, and periodically it sweeps across the eye like a windshield-wiper, spreading the tears during the blinking process.   When the outer lids droop, they close together.  When the third eyelid (nictitating membrane) droops, it slides out over the eye.  Most of the time, it just indicates that the pet is feeling crummy.  If an animal is really feeling low, it may cover most of the eye, which leads to frantic phone calls saying "My dog’s eyes have rolled back into his head!!"  Of course, that couldn’t really happen, as it would rip off your optic nerves when the eyeball rolled around 180 degrees.  The pale third eyelid can resemble the white of the eye (sclera) and that’s what fakes people out.

This cat has Haws syndrome (and I can’t find out who Dr. Haws was, so let me know if you know.  Of course, it could be called "haws syndrome" because "haw" is another name for the third eyelid.  But that’s so mundane… and it doesn’t really explain anything.  Why not just call it "third eyelid syndrome"?  But I digress).  The cat seems to feel fine except for the third eyelids showing.  This is believed to be caused by intestinal irritation, as in an animal with a heavy worm burden, or colitis.  The mechanism is poorly understood (I don’t think it’s the same as "You’re so full of ____ your eyes are brown", but since we don’t really know…).   

There are lots of write-ups on this if you Google it, but I just happened to get this cool picture, so I’m adding yet another piece of informational flotsam to the web.  The syndrome usually resolves over a few weeks as mysteriously as it appeared.  De-worming may help,if that’s what the problem is.  Some may benefit from treatment for intestinal inflammation.  I wouldn’t give them an enema to lower the "brown" content, though.

17 thoughts on “Haws syndrome – the third eyelid is showing.

  1. reed goodwin says:

    Thanks for the info about Haw’s Syndrome.(I enjoyed your sense of humor, as well) I’m sending it to my girlfriend, so she can relax a bit

  2. Cathy says:

    I was so glad to find your article. It describes exactly what my cat is experiencing…the membrane and the upset stomach problems.
    You are an excellent teacher and a very kind person to be helping others this way!
    (It would be a great comfort to have such a knowledgeable and caring person for a family physician!) Thank you!

  3. Well says:

    Wow. I had no idea worms could cause this condition that I previously thought was unremarkable. I’d love to hear more about what other ways worms or colitis can harm my cat. Also, if I’m not sure my cat has worms after inspection of his feces, is it a bad idea to give them the medicine “just in case” without seeing a vet?

  4. Carly says:

    Just came across this article whilst looking up info for my cat. He has just finished a course of anti inflammatories and antibiotics prescribed by the vet as he couldn’t find anything obviously wrong with him on examination (I took him for his third eyes showing). They haven’t made a difference and my cat seems perfectly healthy except for his eyes which have been this way for about 5 weeks. He’s fully wormed. Any ideas?

    • Doc says:

      Hello, Carly,

      I wouldn’t worry about it. It will likely resolve on its own. If he has any discomfort or other signs of illness, then I’d get him looked at again.

    • Doc says:


      I really need to add the disclaimer that I’m just going on personal experience with similar cases. I haven’t seen your cat, so your regular veterinarian is your best source for deciding what to do.

  5. Gretchen says:

    Thank you so much for this info. We have taken in a little feral cat, and he is the sweetest thing but still a little skittish. I was worried when I saw this today that he had suffered some kind of head trauma. In his case it might very well be a heavy worm infestation as I have had little or no success in getting him to eat anything with worm meds in it. Am hoping they make something that tastes less like medicine and will continue to try. Any suggestions welcome.

    • Doc says:

      Hello, Gretchen,

      You would have to see a veterinarian, as the product is not over-the-counter, but there is a dewormer called Profender that is applied trans-dermally. You just empty the tube on the skin (underneath the hair) on the back of the neck.

  6. Gigi Vignets says:

    Doctor, thank you for dedicating your time to help pets and their owners.
    My 5 years old cat got the third eyelid about 3 weeks ago. I tried terramycin ointment and didn’t help. I took him to the vet in the past week and he said that’s probably calicivirus and prescribed a triple antibiotic eye ointment. Oliver eats well, no fever , in general in a very good shape. I bought a lysine powder and sprinkle it on the dry food for all my cats. I also bought a lysine gel and started giving it to Oliver twice a day to boost up his immune system.
    After 5 days I took Oliver to another vet because the ointment didn’t help. She said he looks healthy, no fever but just in case she gave him a Convenia injection. She recommended to continue with the Neopolyback ointment. If there’s no improvement in a week , she recommended to do a blood work. I have no peace. I’m so upset I can’t help my baby. His eyes are also a little watery. I mentioned to the doctors that Oliver has been sneezing more than other cats during all his life. I was suspecting that’s maybe is an allergy but than the first doctor diagnosed him with a calicivirus. The second doctor thinks there’s an internal problem. I noticed he vomited a can food I gave him yesterday. Today morning it came to my mind to deworm him with strongid. I though that won’t hurt . All my cats are strictly indoor but I have 3 dogs and I know there’s a possibility of contamination with worms. Today, I found your blog and I’m so grateful that you posted the info about the third eyelid! I live in TN . Otherwise I would take Oliver for an appointment with you!
    Thank you for your time, doctor. Could you recommend anything else besides what I’ve been doing?

    • Doc says:

      Hello, Gigi,

      Some cats with chronic eye problems have herpesvirus. As with people, herpes viruses remain latent in the body, like a person with cold sores.

      Twice daily famciclovir helps most of these cats. (Given orally – there are anti-viral eye drops, but they tend to be pretty irritating to the eye).

      You might talk with your doctor about that.

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