Small white bump/pimple on my dogs belly

Hi does anyone know what is it? It's similar to an acne/whitehead. Should I be concern?

growth on dogs back

this is something that was there a year ago (unless that was something else and trying to monitor I've crossed the bumps we tried to show it to the vet a few times but in the end after visit and emails we only got that they couldn't find it. i sent another photo now 11 months later but am not optimistic, anyone have any idea? i know we need to bring it up again, but we usually don't get answers. sorry rambling

Dog gets aggressive toward cats in evening

I got this little lady about 3 weeks ago and everything has been going better than I could have hoped. Until the Sun goes down. She gets along great with my 2 cats. Always going belly up to show she’s a good dog. Then night comes and she growls when they come near her and wants to go after them. (Quick note on the cat…she won’t run!) She knows that cat is the boss and all day treats her with that respect but at the end I’d the day it changes. I assume it’s some kind of separation anexity. What do I do?!