Animal companions (and wizard familiars for that matter, although that's largely only relevant in NWN1) automatically level up when you do. You do not need to take any further action to advance them.

The Ranger's animal companion is rather weak (a 5th level Ranger's companion is equivalent to a 2nd level Druid's). The companion's hit points improve every other level, so he did not get tougher when you went from level 4 to 5. Expect to see some improvement when you go from level 5 to 6.

Thanks....If i remember right my wolf in nwn1 leveled up every time I did but it's been awhile since I played.

Yeah, animal companions seemed stronger in NWN1.

You could consider taking the Dinosaur Companion feat. Sure, it costs you a feat choice, but rangers get most of the combat feats they -really- need anyway as they gain levels. And the dinosaur is much stronger than the usual companions. Not to mention it's pretty cool in general.

Edit: if you have Storm of Zehir, that is. Otherwise you're out of luck, I'm afraid.

Animal companion rules were changed from 3.0 to 3.5, so I'd expect there to be a corresponding difference between NWN 1 and 2. To my annoyance, I can't seem to find a detailed description of the NWN1 implementation (nor do I have the game handy to check the numbers myself) and the actual 3.0 rules are so open-ended that they provide little guidance as to what NWN1's rules might have been. The GOG installer includes SoZ by default. While there might be a couple people here with CD versions, I think you can safely presume that people are running the game with all expansions and patches unless they explicitly state otherwise.

Good to know. Thanks. (I actually have the GOG version, but I don't think I ever installed it since I also have the disk version. Not quite sure why. A sale is probably to blame.)