Juliet's Nose
My Harper Lee has snorting episodes, no blood though. She has allergies, the snorting just started not too long ago, she has sinus drainage and the like just like me.
As for diatomaceous earth being harmful, only if you inhale it and then only if you make a career out of inhaling it. Just like any powder, baby powder for instance it can cause irritation if you inhale it so don't you inhale it or let your dogs inhale it. I wear a bandana when I sprinkle it on the ground for the pups. Once laid on the ground it won't be an irritant nor is it harmful in any way for your dogs, cats etc.
I have been using FOOD GRADE DE for years now, and it has kept my flea/tick population at zero. There are no ill effects on doggies or humans.
Best,
Kate