So....this is probably a ridiculously stupid question...

I'm no vet or medical expert but I would guess it's more of a shared allergy to something.

I remember when my parent's dog was a puppy, he caught 'pink eye' - my big sis had it as well so we thought it was the same, but we asked the vet and they assured us it was simple coincidence.

I would think you're all bothered by an allergy to something similar - pollen or something.

hapnthatch

I know that there are zoonotic? sp? diseases that can go back and forth

These sites describes some of the zoonotic diseases that involve dogs, but none involve red eyes.
http://oregonvma.org/care-health/zoonotic-diseases-dogs
http://www.canismajor.com/dog/zoonot.html

The only viral zoonotic diseases that I have seen are rabies and a type of flu which is not in the U.S. (H5N1). 

Red eyes can be a symptom of tick-bourne diseases like Lyme disease or Rocky Mountain Spotted Fever.  Both you and your dog could have been exposed to ticks.

I really think that allergies and eye irritation are much more likely than any disease since there are no other symptoms.

There are some viral and bacterial things that are zoonotic (affect all 'animals' including humans) -- but what you're seeing is very likely allergy

Even human "pink eye" (conjunctivites) can be either bacterial or allergy-based.  And sometimes it can go from allergy TO bacterial (because once the tissue is inflamed it's more easily and readily susceptible to bacteria).

If you can find Similisan Eye Drops (it's a homeopathic but it tends to be pretty easily found in pharmacies and even my grocery store carries it).  They have a "Pink Eye" version that is awesome for both dog and human eyes. 

Avoid stuff like Visine -- like ChapStick it can actuall *create* the problem it's used to get rid of.  It feels good for a while but ultimately it actually can dry the eye *more*.  And eye lubricant that doesn't have preservatives is better. 

I'm really prone to pink eye (the bacterial kind) and I always have to have stuff at home to use instantly when I get "THAT" itch in my eyes.