Once upon a time, I had a nutcase named Milla. And she went flying up, as I was stooping down, and my forehead exploded and my legs went weak and my stomach turned over.
Milla's eyes went all blood shot. I took her to the vet. The vet looked at me kind of funny. She said she normally only sees that when dogs have been in car accidents, and she asked how I was. She seriously seemed more concerned with me than the dog.
Milla did not eat for two days, but that was the extent of her injuries. She remains as nutty as ever. And her rock-solid head is as viscious a weapon as it ever has been.
If you do not have any event that might have caused your pup an injury, I would have her checked out.
Yukon had bright red eyes one evening so I took him to the vet ... it was diagnosed as DRY EYE ... some ointment and eyedrops resolved the problem (sometimes it's a lifetime problem, Yukon was lucky that it was easily resolved). I also have dry eye and can tell you it's extremely painful when it's flaring up (usually my daily eye drops keep it under control).