>>293839
That is more of a grey area. On one hand, the only one who can speak to animals is the one who has a magical talent for doing so, while its entirely possible she merely listens to what they say the same way dog owners listen to the mutts barking to guess at what it wants.
On the other hand, Iron Will's goats worked as his assistants, helped him out on stage, yet never said a word. Other than BAAAAAHHHH, anyway
I suspect the show will never give a clear answer on that, since, like the sentient sheep and cows being kept as cattle by the ponies, it raises a lot of iffy issues about pony society and whether or not non ponies are regarded as slaves or animals.
Regardless, the deer depicted in the show where shown as nonspeaking pets and animals, like regular dogs, cats and rabbits, while the deer in the comic where citizens of a different country, so keeping them locked up or treating them like animals would likely result in some objections from said country.