Don't know if this is it, but it sounds like it might be what you're looking for: Runt of the Litter series by graceandfire. Here's a link: http://archiveofourown.org/series/2542

Hope that helps!

Thank you so much! This is one of the fic I was looking for. :D

there was "pack leader" but it sam who commands hell hounds, while dean pretends not to like them. sorry can`t find my link for it :(

Thank you.

I think bard2003 is referring to Leader of the Pack by astolat - amazing fic! (Sam/Dean, s3): http://intimations.org/fanfic/supernatural/Leader%20of%20the%20Pack.html

There's also the terrific Happiness Is a Warm Three-headed Puppy (Sam/Dean, s4) by squeakysnow. The story is locked, sadly; you can PM the author to request permission to read.

Thank you so so much! These are some of the fics I was looking for. :D

There is also a year nad a day by Subtleshadeofgrey with Dean beeing "given" a Hellhound by the crossroad demon! Go read it, it's great! :D
http://www.fanfiction.net/s/4943328/1/bA_b_bYear_b_and_bA_b_bDay_b
Warning: It's a gen Mpreg story incase you don't like these kind of fics.

Winged Golden Tiger

Thank you for the link. :)