So how are dogs changing the way they smell? Are we talking about pheromones? If so then your nose is a lot more sensitive than mine! My dogs seem to smile and wag their tails when they're happy and growl when they're mad and wimper when they're sad. They communicate a lot with other less obvious audible and visual body language too. As far as smells go...... um no... cept one of them passes a lot of gas, but I'm pretty sure thats from my son sneaking her his breakfast ever morning rather than her moods. <img src="/images/graemlins/grin.gif" alt="" />