Quote Originally Posted by Karen
If you are taking a stranger's picture and planning to sell it, you need to obtain a release from them. However, posting a stranger's picture, with no financial gain, and without identifying that person in any way, is pretty harmless.
Not to mention completely legal as well. And that applies to pets, too.

Now of course if the pet owners find out later on and don't feel comfortable and ask the pictures be taken down... no big deal. But as a photographer, if you take the picture, you own the picture and can distribute it as you will if there is no financial gain and you don't give their identity out, etc.