I have a brother with 6 dogs and at least a few cats. They are not fixed, vaccinated and a few are kept outdoors in a sideyard. he is always making snide remarks about my one little Puppy. She has all of her shots, and everything. I find it interesting that these are the people want to say mean comments about other family member's pets.
I'd like to say, "when you start treating your own animals better, then will talk."
If it is someone I don't know and they comment, I plainly ignore them. most people love a yorkie, and want to come up to her and pet her.