So started compiling and cross referencing Bases (where the Core says it is allowed) for my "Codex of Hermetic Magic" project. This has produced the strange situation where it is easier to speak to a dead animal (InAn Base 5, from InCo) than a living animal (InAn Base 10) be RAW.
While it looks very odd at first, after a little thought it makes sense.
A living animal can offer conversation and information without being directly asked. You could know what an animal is trying to communicate even if it is not trying to communicate directly with you (such as what a bird is singing or a squirrel is chattering about).
A dead animal would be only marginally similar to Whispers Through the Black Gate, since it is the dead animals corpse rather than a spirit that you are communicating with. Closer to speaking with a tree or rock really. I am leaning towards adding a specifying restriction.
"It will only answer direct questions..."
(possibly with) "...that it could answer while alive" or "...that it knew while alive"
(possibly with) "...and not lie"
EDIT: You also have the Base 5 "understand the meaning behind animal sounds/communication" (from InMe) which would allow you to understand what an animal is trying to communicate, without the ability to communicate back. So you could learn that Lassie is hysterical because Timmy fell down the well (again).
Something I just saw, it's easier to have two-way communication with an Animal (InAn 10 as you already stated) than to have two way communication with a human (InMe15, from Core Guidelines). Not sure I've ever noticed that guideline before.
Lots of InAn things are slightly easier than InCo or InMe equivalents. I'm going to write it up as animals not having a soul and being simpler than humans (Cunning, if they are Intelligent it requires the higher Mentem Bases).
Part of my project is to remove the implicit transfer of Bases between certain TeFo. While several state things like "see this TeFo for ideas", they do not cover which Bases or what changes need to be made. I am adding all the appropriate Bases, avoiding any which are higher/lower than those already in the TeFo, and adding clarity.
I am also going through and pulling Bases from published spells/enchantments which were not added. For example ensuring conception in humans is found in a Charged Item at Base 15. So I added that. And since Magi might want to do the same for animals, I looked at CrAn. Hummmm... Base 15 CrAn is create a mammal, most likely where they got the Base 15 for ensuring human conception. So for animals, the Bases for ensuring conception are the same as the Base for creating an animal of appropriate type.
I suspect InAn being simpler than InMe is because animals of the same species all speak dialects of the same language (or so the Animal Ken rules would have me believe), whereas humans all speak very different languages because of The Tower of Babel. Perhaps a holy mage or interested theologian could discern important things about natural theology from this.
You could also do some hand-waving to avoid this, in that the InCo spell resonates with the intelligent spirit that was housed in the corpse - an echo of a ghost.
While Animals don't have ghosts, so there is nothing in the Animal corpse to resonate and provide answers.