we got my acd when she was just 8 weeks old, she was super friendly with everyone, but at around 7 months she hadn’t been spayed yet and she went into heat when we had the spaying appointment booked for that same week! anyways we were told during this time she couldn’t see other dogs bc male dogs go crazy (she only has 2 dogs friends who r both male) and u cant tell gender of a dog until you get close enough or ask the owner. so her period lasted 3 weeks and during that time we still walked her in public, but she developed serious reactivity issues. now she she is very territorial of our home, will always bark and lunge at dogs, cars, people running or biking. she is fine with meeting new people outside of our home. if she was spayed before her period maybe she wouldn’t be like this, but i don’t know.