[yorkietalkjilly]

I'll disagree a just little bit on the vet office smell being that important a factor in dog behavior for the most part in and off itself but strange smells can certainly add to the already insecure situation of the weaker dog. In the wild or with feral dogs or where no vet office visit has ever or in the home where a vet visit has not yet occurred, weak/sick dogs are still often attacked by other pack members; and if they are too small to attack, fitter, younger pack members will often shun/ostracize a weak dog.

It's the weak dog's continued prey-like behavior or mentality/energy that triggers the urge to attack them and it's purely instinctive to most dogs, like eating their own poop, sniffing each other's butts or turning around and around before lying down. Even little toy Yorkies are still 100% canine right down to the marrow and killing off the old, weak, insecure-acting or infirm is just Nature's way of purifying the gene pool.