A tied cock should be able to still go deeper, but only slightly. Allowing for a back and forth pumping motion but only over a short distance which represents the area behind the knot between the base of the of the cock/groin and the knot.

Also the tail, it would be nice to be able to turn off the tail.

Spread & exposed vulva when excited for the various canid species would be a wonderful addition.

I'd like to see this as a rare condition that characters occasionally posses the trait for, and perhaps as a modification trait that can be applied to subjects, NPCs, and player after some sort of research and development.

Beast wolves? Very large perhaps?

I mean, how else are you going to know the fox is full unless it has a runny nose?

Additional suggestions: Self suck, paint the ceiling, orgasm for an excessive amount of time (or without end,) larger or smaller size, cock modification - make a non-canine species grow a knot (or even a canine gain equine features,) lactation, gushing.

I'd like to see this, but only when its a large object. Perhaps when something is disproportionate.

All the way through for tail holes sounds possibly hot, either they cough it up, or it gushes out their mouth and/or nose. As for filling the vagina beyond capacity, a belly button suddenly popping up could be a funny indication.

If added, at the minimum, I must be able to write dirty words on a character's forehead. Not so sure it'd work well on genital