I had a neighbor with a very loud dog. I left a note the first time, and a few times after that because they were never home and left the dog outside to bark and roam the neigborhood.
Some of the neighbors said it didn't bother them, others said it did. The dog was RIGHT NEXT to my house however, and sounded like it was barking in my living room. When caught them at home I politley asked that they do something, I got a lot of hostility and "WTF are you gonna do" type attitude. I mentioned that others in the neighborhood were also upset, they didn't care much.
This is not a fair position to put your neighbors in, and can be very frustrating for them. I own my home, I can't just up and move because of a barking dog or loud ass with a fart can.
However, I did know their landlord and gave him a ring. He was pissed because he told them repeatedly they couldnt have a dog. About a week later there was a u-haul in front of their place.