There is still actually 5, but Arya's Nymeria is stuck in the wilderness and separated from her main character.

Rickon's Shaggydog is not seen for you didn't see Rickon in this episode.
Robb's Grey Wind is not seen for Robb has a very very brief scene saying you shouldn't wish for yourself to be dead Bran.

So the only two wolfs we could have seen this episode was Bran's Summer and Jon's ghost. The cut out the naming of the wolf Summer and the three eyed crow scene (which should have taken place at the end of episode 2 and the beginning of episode 3). They couldn't really glance at Summer when Old Nag was telling her story about the Others and how horrible winter was for showing the wolf then would make the viewers not fear for the starks for they have magical wolfs to protect them. They could have showed Summer sitting on the floor or something when Robb walked in but they didn't for some reason.

I really don't see why they didn't include Ghost at Castle Black, it would be easy to show just a quick glance of him in the background. Especially since it was made very clear in the book that during this timeframe of the series that Jon saw himself as alone with only Ghost as a friend, this was before Tyrion showed Jon that his fellow mates were all outcast and thus "bastards of society."