Many researchers are focusing on animal intelligence and language. At this site you can link to the interesting articles on the topic on animals and relevant human studies.
Dogs can understand receptive language of over 200 words.
Dogs can learn to associate specific gestures with specific meanings.
Dogs can detect various chemical previously not explored....
Dogs can classify objects..
Birds can recognize themselves.... http://www.sciencedaily.com/releases/2008/06/080613145535.htm
Horses can learn to associate specific gestures with specific meanings.
Horses think through problems.
Horse learning with positive reinforcement..(you may need to log in to horse mag)
***Human research relevant to facilitating animal language development***
Language develops in bursts...(human)
Language development stages (human)
Language from whole to part (human)
Language lateralization (human)
Language learning stages and lateralization (human)
Features of language (human)
Talking to babies helps langauge development (human)
Signing Language in Humans
Babies can Sign