Apparently when my friend tried on her cosplay the other day, wig and all, her dog freaked the eff out. So I don't think it's just scent for all animals.
My dog's old as hell, and all her senses are going, so I don't think she'll react differently (she barely knows where she is half the time, poor thing). Plus, I've had her since I was 10 years old, so we've watched each other grow up. I don't think the physical changes will scare her at all. My mom's chihuahua, however, might start acting differently (she's not even 2 yet). We'll have to see, although she's surprisingly smart. I could see her making her peace with it. I don't think the cats will act differently, though. They're my babies and I don't think anything could make them leave me alone. ^^;
To be fair, as far as scent's concerned, I feel like I already have quite a masculine smell. When I was taking DHT-blockers last year, I smelled much more neutral, and as soon as I stopped them, I got my man smell back. So I'm not sure how much that's going to change, or how much stronger it's going to get.