I don't remember every detail. I remember inuyasha and kagome wanted to be together but kikyo cursed him and turned him into a dog. They were only able to break the curse when they tried to have sex with him being in dog form. I remember kaede thinking that her sister was a pervert. Does this ring any bells?

This is not the one you are looking for, but I thought you might like to read it since it's got a similar storyline. It's in the one-shot collection The House Of Lemons
by Silent Death and Rinseternalsoul on Adultfanfiction.com

To Break A Curse By SilentDeath
Summary: Kagome found a stray dog on her front door one night. She brought the animal in and now takes care of it. But the animal has strange mannerisms and seems to understand her. Now, Six months later, Kagome finally asks the animal who he really is. She never expected him to find a way to answer her, nor did she expect the dog to come along with a curse…..
Rated MA!!