I always wondered; why are the bodily fluids, etc. that accumulate (and usually dry out) in the corners of a dogs (and cats too, I think) eyes black?; but in humans, it is not?

2 Answers 2


This is common to many dogs I've been with.

This link http://m.petmd.com/dog/general-health/5-types-dog-eye-discharge-and-what-they-mean talks about several different kinds.

I believe the one you're talking about is the dark brown/red crust (#3)

Light colored dogs often develop a reddish brown discoloration to the fur below the inner corner of their eyes. This occurs because tears contain a pigment called porphyrin that turns this reddish brown color upon prolonged exposure to air


Humans tend to keep themselves cleaner than dogs do. The difference in color is dirt buildup. Ask any girl who doesn't wipe off her mascara before she goes to bed what color her eye boogers are in the morning - black from the buildup!

Of course dogs don't wear makeup, but they DO dig in the dirt, do their business outdoors, go for walks, stick their noses and faces into your garden and anything else that fits their fancy! All this is done without a shower every morning or evening. If you started a daily routine of wiping your dog's eyes with a "pet eye wipe", the discoloration will become significantly reduced.

  • 1
    I do clean it daily. Seems to start black. That's actually why I asked.
    – voices
    May 24, 2017 at 14:43
  • Does he have any kind of ear gunk? And does he have any pinkness, redness or swelling around the tear duct? Allergies can cause discolored eye discharge and so can fungus, like yeast or a bacterial infection.
    – Christy B.
    May 24, 2017 at 14:54
  • Do you have a pic you can post? I can edit/add to my answer depending on responses. Thanks!
    – Christy B.
    May 24, 2017 at 14:55
  • Nah, he's fine. He has no issues. I'm just asking out of curiosity. I think you'll find it's just the colour of it.
    – voices
    May 24, 2017 at 15:34
  • 1
    So check this out! Point #1 talks about normal eye goop or dried crust, most prevalent in the morning or after a long nap...Made of an accumulation of dead cells, oils, dear, debris, dried tears and mucus. m.petmd.com/dog/general-health/…
    – Christy B.
    May 25, 2017 at 2:59

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.