Dog's watery eyes

HI there,
I have a 7 yr. old Sheltie who's eyes starting watering today out of nowhere. She seems like she feels OK but I have never seen her have this before. Normally her eyes are very dry and I never have to wipe them. They also don't look as perky as usual. I am worried because I am having a major surgery on Tues. Feb. 17th and tomorrow is the Friday before. I don't have alot of time to wait and see if it gets bad. I would love your input. Thanks so much.
Sue

Could be an allergic reaction to something airborne...is it just clear tears?

Sometimes dogs will get conjunctivitis which is a generic term for irritated eyes...it's not serious (just bothersome for the dog) and inexpensive eye drops from the vet clears it right up.

One of my dogs occasionally gets teary eyes. We have no clue what triggers it, but a couple of days on his eyedrops & he's all better.