I remember hearing that normal silicone caulk used for windows and such has a fungicide in them, to help prevent the area around the windows from rotting overtime. My
LFS said this fungicide could be lethal for animals if it leached from the caulk.
But i'm not sure how true this is, i often don't trust my
LFS. But for what it's worth that's why i've been using the 'official' stuff even though it's a pain to use alot more expensive.