All Girls Like Ponies

Films - Animation

 * Jessie's previous owner Emily in Toy Story 2. At least until she grows older...

Western Animation

 * Ginger of As Told by Ginger likes horses enough that her room is decorated with a horse motif.
 * Tina from Bob's Burgers like horses almost as much as she likes zombies.
 * Craig of the Creek takes this Up to Eleven with the Horse Girls, who are obsessed with horses to the point of acting like them.