Y'know, the beginning of the chapter talked about canine reproduction, so I looked it up and it really didn't seem all that traumatizing compared to human reproduction, so I'm not sure why they made it seem so dramatic. On that note, apparently canine things don't actually get hard until after they're inserted, so the last panel doesn't really make sense (unless the author is implying she tried to... Ehem...). Ntm dogs can't reproduce unless it's the "right time of the year".
On another note, that last panel made a great "no context" pic to send to my friends. Lol.