sucking

I have a Shepard mix that’s one of the rare ones who will hop up in my lap and as soon as I pull my cock out, she muzzles it and starts suckling hard until I cum. She works hard for her treat at the end ? anyone else have a dog that does this or have had an experience like it?

Was wondering if anyone else was into this. So I live with my sister and her black male lab/collie(maybe?)mix. The dog is fixed. Long story short, practically nothing sexual happens; not only due to him being fixed, but he act uncomfortable with touching his sheath or anus. So all I ever can...