What happens to animals when their Int goes up?

[Klaus]

As written, yes.



Certainly it's important. Elementals, for example, specifically mention that they speak Aquan/Ignan/Auran/Terran, which means the 'unless otherwise specified' clause applies; they do not speak nor understand Common. The animals (untemplated) on the Summon Nature's Ally list don't understand Common, so you need Speak With Animals to tell them to do anything more that "Get 'em!"

A Celestial Badger, on the other hand, understands Common.

-Hyp.

A summoner can use Handle Animal to push a summoned animal to do something other than "get 'em".

 

[Notmousse]

Another side effect of the high Int animal is that they no longer have need of 'tricks'. They simply understand you and obey (assuming it wasn't stupidly dangerous).