My dog has red, painful, maybe swollen third eyelids. It’s not cherry eye. What is it?

Started last night with his left eye. The third eyelid appeared red and swollen as though something was in his eye. He did not appear to be in any pain and there was no discharge.

This morning, however, his left third eyelid is very red, maybe slightly swollen, and there was a white discharge from the corner of his eye. His right third eyelid is now also red and appears slightly swollen. He consistently rubs at his eyes with his paws, and will not open his eyes very far, if at all.

His third eyelids are not retracting very far either, especially the one on his left eye; it covers half of his eye.

I do know one thing though, and it is that this is probably NOT cherry eye. There is no swollen or protruding gland visible.

I have not noticed any other possible symptoms excepting that he appears more tired/less energetic than usual.

To recap: both third eyelids appear red and slightly swollen, the third eyelids are not retracting from his eyes well, there is a white discharge from one of his eyes, it appears painful to him, he appears tired.

Are there any other possible symptoms I should look for? I am taking him to the vet today and I would like to converse with the vet about what possible diseases/infections this could be. It’s a small town vet, so I am assuming they don’t have as much knowledge/experience as a larger city’s vet.

Also, are there any sites on the internet with pictures of dogs with illnesses of the eyes, etc, so that I may compare different symptoms?

Thanks a lot for any helpful input.
Dogs have what’s called a “third eyelid.” It’s an eyelid that closes around the eye when they sleep. If you peel back a dogs eyelid when it’s trying to sleep (not recommended) you should be able to see it. It is normally a light pink color.
ALL dogs have a third eyelid. There is the upper eyelid and lower eyelid where the eyelashes are located, and an additional, “third” eyelid, that moves up from beneath the lower eyelid to cover the eye when the dog sleeps.

The third eyelid is responsible for approximately 30% of the eye’s tears.
A certain gland within the third eyelid can sometimes swell and protrude from the eye resulting in what is commonly referred to as “cherry eye.”

ALL dogs have a third eyelid.