Well I don't know about dogs in general, but Keiko has definitely gotten more vocal as the years have gone by. She's now 9, and for the past 2 or 3 yrs I can now get her to howl on command (sort of.......I have to howl along
). It is something I have been trying to do for years but never accomplished. She will also sometimes greet you with a howl now. Also w/i the last few years she has gotten very vocal when playing with other dogs..........
.but only on our property, at the dog park she's still quiet.
Of course she's also gotten more grumpy in her old age........lol
........but I guess that's to be expected.