For the most part I keep them out although they don't seem too interested beyond kind of wondering what I'm up to in there. I keep my dogs out of the grow room for the safety of their eyes mostly but also to help keep the amount of hair in my grow area down. They don't even shed very much but you'll be amazed at how much hair you will find in your tent and on your plants, especially if you have long hair and/or a beard. I try to keep it down because I don't want to smoke any more hair than I have to and even if you see and remove it before harvest it tears up trichomes. During veg it's no big deal but I still try to maintain good habits like keeping the pets away, keep the floor clean, brush my hair before I go in, etc. The cat is not allowed in the grow room that houses the tent at all, no exceptions. She might be just fine in there but she might fuck something up, I'm not willing to gamble with my grow.