Very interesting. I think it's unlikely that we are the only species that ingests materials/chemicals that make us feel good, aside from providing any nutritional value.
Animal drunkenness is a well documented phenomena. Many species of monkeys and apes will "recreationally drink," given the opportunity. Interestingly enough, the rate of "alcoholism" among many simians is inline with that of humans.
Jaguars in the Amazon rainforest are known to consume leaves of the Caapi vine to get high, because it seems to improves their ability to hunt effectively.
The Caapi vine is also the main ingredient in the psychedelic Ayahuasca brew drunk by the Amazonian shamans.