While visiting my mother-in-law this weekend my dog started acting funny towards others, kinda protective over me. Well while visiting, my 12 year old brother-in-law had a friend over, a young boy the same age at my brother-in-law, and anytime this boy would walk near more or come close she would start barking and acting kinda aggressive, but would never charge at him, she would just stay right next to me she would bark. This is very weird for her because she loves everyone that she has even been around and we thought it was very strange she’s never acted like this. When talking to my father and sister after returning, my already pregnant sister stated that she might be feeling a change in my body, possibly being pregnant and that she is now feeling this change and becoming protective over me. My question is, can dogs really feel this change and could this be a real possibility why she’s acting strange lately?