Yes, our 4-mo old pup developed eye gunk. Our regular vet couldn't figure it out and referred us to an ophthalmologist who's first question was, "did you have a real Xmas tree?" Ophthalmologist said it was a common allergy for pups and that they often outgrow it. Our pup is now 3 and was fine this year (without meds--he did require eye drops the first 2 Christmases).

I think my cat was alergic. She'd get itchy skin and then chew the hair off behind her tail. Only did it when a tree was in the house and in an area she could get to and rub up on it.

It may not be the tree, but something which has been sprayed on the tree.

This is the first Christmas we've had without a real tree. Last year our lab was miserable with red itchy eyes and pimples in her snout. So far our theory of it being the real tree is holding true. She has not shown any signs of allergies this year. I was just curious if this has happened to anyone else.