Well it might just be me but we used to do it a lot then I started noticing that sometimes cum or something would leak out and it was green and didn't smell nice so I'm assuming it was something bad. Since I implemented my rule I have not seen anything like that since. I imagine they are similar to humans where the chemical balance can get out of whack and it's not good for them. And get infected and whatnot. And her health is the most important to me, I would completely quit if It affected her health.