Nothing big here, just a comparison on Balto's and Jenna's designs--mostly their facial designs--throughout the 3 films.  They changed a lot and I, personally, love their first designs above all else. (Others think differently, that's your opinion and you're bound to it).

Now, as much as I hate Balto 3, I think they did a slightly better job of making Balto look more like his original self--at least more than Wolf Quest.  I, sadly, can't say the same for Jenna.  (Some shots more than others, though)

So, the basic idea is that I'll be putting together similiar shots/facial expressions from all 3 films (I also tried to pick similiar body movements, but please forgive me if they're not all exactly the same; body motions aren't really the focus of this article, but I tried to find the best match.)
 

Personally, I like this picture (below) a lot because it shows a very similiar angle of Balto from both movies (1 and 3) and clearly shows their differences and similiarities in style.
 One of the most interesting things to me about character design is the style of every animator.  Take, for example, the picture below.  The images of Balto look pretty similiar; they get the message across that that is indeed Balto, and not some other random dog.  However, what makes the bottom picture so much different than the first one? 
Slight tilts in the eye patch, fur texture, muzzle structure, etc.
Tiny details that only have to be altered slightly to make a character different from sequel to sequel.  What's more interesting, even in the original movie, the same character is not often drawn by the same artist (however, that difference is usually not as noticable due to clean-up artists and the fact that animated characters are usually drawn by people in close-working teams; but that's another topic for another day.)
 

Jenna
 Like the pictures of Balto, Jenna's original design looks simple but when it actually comes to drawing her, it can be very difficult (aside from the fact that I am not her creator and therefore can never truly draw her in her original animator's/animators' exact style.)
I purposely put that second image of Jenna from the original movie to show that her neck marking doesn't always have that curve that it does when she's usually seen at a 3/4 angle (notice the sequel Jennas don't have the curve; i didn't want it to look like that, in particular, was the fault of the sequel animators; it is true to her design)

 
 
(Yes, I know Jenna isn't howling in the original movie; I just wanted the similiar head angle here)

Based on the what I know about character design and animation; the movies themselves and the images here, the animators from the Balto sequels tried to at least make our heros recognizable.  If those of you who have tried to draw Balto or Jenna--beginner to professional--it's difficult to get those two characters down just "right."

So, that about wraps it up.  Please tell me what you think; I'm practically obsessed with character design and sequel differences, especially from this movie, and I love to hear other's opinions!