Just a little mod I made for myself and wanted to share with people not into creating their own mods. I enjoy traveling through Skyrim on horseback and having a guard dog around the house, but simply hate their loud sounds.

Simply download with mod manager or place it manually into your data folder.
No conflicts that I know of, but I haven't tried any mods that change animal sounds, so no guarantee there.

Small update: added an .esp file with just the dog sounds reduced. So now there's "Quiet Dogs" and "Quiet Dogs and Horses". Only activate one of the two versions in your load order or, if installing manually, only choose one version.