You don't always get a hybrid when you hatch with a pet you only have a 25 percent chance of getting ice hound and a 25 percent of getting a sandmen 25 percent chance of getting a colossus and a 25 percent chance of getting a orthrus sorry to say you just got unlucky.
You didn't get an ice hound because there's a high chance that you'll get your same pet back if you're mixing level 48 pets. I mixed my helephant with a stormzilla and ended up getting my helephant back again. I don't like how much money we spend on hatching just to get our same pets back. I wish KI would do something that would make sure we at least got a different pet. But if you really want an ice hound you should keep trying, I've seen a few around and they're Awesome :-D