I maxed out on my wordiness D:
She could feel it- the wave of pleasure that had been increasing was just about to crest and- with a pop, the fiend shattered at the knot which forced its way in. Crying out sharply, her body locked up, freezing in place as her orgasm washed over her, the dog likewise still while his body emptied itself inside of her.

Taking a shaky breath, her body calmed, heart slowing as the knot inside her deflated at its own sweet pace.

He slipped off her back, seemingly taking a moment to admire his work, before nipping at her hips.

“Good boy.”