Yes, find out her reasons, if you already don't know.
And I can speak from experience of being a mother for nearly 26 years,
"because I said so" IS a valid reason in "mom talk" and actually you live under your mothers roof and when you live under your own roof you can make those decisions for yourself. Your mother knows you better than we do, she has reasons behind it I suspect. And some people just are not "pet" people or even "dog people".