Last year I grew outside. As I would check each plant my dog would follow, pissing on each one -- until I caught him in the act. After that they stopped yellowing and seemed to perk up some.

This year I grew inside. Thought I had a severe pest infestation cause all these bottom leaves were getting chewed up -- but couldn't find the little buggers. It, too, was the dog. I wondered how a caterpillar could strip a while branch. Once again, had to catch him in the act.

Both problems have been permanently abated (no, I still have the dog -- and he's not dead ... yet)