Inspired by this question
Most animals have an intelligence of 1-2 in PF. But should you cast Fox's Cunning on one and raise it's int to (say) 6, does it become a magical beast automatically (with better hit dice and attack progression)?
By RAW - It doesn't directly say.
It says animals can't have an intelligence over 2. A spell like Awaken changes the type and grants it more intelligence permanently. The restriction on animal intelligence isn't fleshed out beyond "intelligence score of 1 or 2." So there's really no good RAW answer that I'm aware of.
Given that spells (like Awaken) that change your type usually say so, I'd have to expect that it's not intended for a temporary buff to change your type, HD, and BAB, not to mention break any spells that require the target to be an animal to work (so no Animal Growth on your animal if I first give it more intelligence?).
As for how that restriction works, I see two ways of doing it:
Either way, actually having it change the type on the fly would be really odd.
I doubt it.
If it did, it would have some additional wording stating the affect when applied to animals like is found on the awaken spell.
Usually there's no practical difference between providing a bonus to a score and actually raising that score, but your particular example hits upon one of the few points where it matters. The spell you mention provides a bonus to the creature's Intelligence, rather than actually raising the creature's score above 2, so the creature's type does not change.
In addition to Magical Beasts, 3.0 had the Beast creature type, which was used for creatures that didn't correspond to things we'd find in nature, but were not actually magical in nature. The Owlbear was probably the most famous example of a Beast, but other "smart animals" could have fit in here as well. 3.5 folded the whole creature type into Magical Beast, though, and PF seems to have followed suit.
Fox's cunning provides a temporary boost to an ability score.
d20pfsrd says the following about such increases:
So, RAW neither the Fox's Cunning spell nor the relevant general rule says that it changes type so no type change occurs.
Now, I assume the next question people are going to ask is what happens when someone casts permanency on Fox Cunning in order to trigger the following bolded text from d20pfsrd:
Whether or not those other bonuses and statistics include creature type is irrelevant. This is because RAW you can't use Permanency on Fox's Cunning. The Permanency spell linked lists all of the spells that can be made permanent. All other uses are only allowed via DM discretion.
No. See the descriptive text for the following items, which raise or mention an animal's intelligence in a way which indicates or implies that increasing an animal's intelligence score doesn't automatically change its type:
See also the text in the Advancing Companions section on Animal Companions towards the bottom of this page (Also in Ultimate Campaign), which also clearly implies this isn't the case, with sections like:
"If the companion's Intelligence score is 2 or lower..." and "Training an animal to be smarter, more intuitive, or more self-aware is less easy to justify—except in the context where people can cast spells and speak with animals"
and the section titled "Intelligent Animals" (also from Ultimate Campaign. Link goes to same page, scroll down) which just flat-out says this doesn't happen:
"Even if an animal's Intelligence increases to 3 or higher, you must still use the Handle Animal skill to direct the animal, as it is a smart animal rather than a low-intelligence person (using awaken is an exception—an awakened animal takes orders like a person)."