Ways to turn your Animal Companion into a shape changer

[SangoProduction]

Are there any? It would make such a great combination.

I appreciate those spells that change your animal companion or yourself into a single other creature, but not exactly what I'm looking for.

And by "shape changer" I mean, give it some sort of ability to wild shape, or polymorph itself, or use an ability like the Changeling. [Wands would probably work for this purpose, if you have an AC that can use them.]

[sleepyphoenixx]

Take a level of Hierophant. Select "Power of Nature" as your special ability. Give your animal companion one or more uses of your Wild Shape ability.

[Uncle Pine]

Be a Druid.
Take the Enspell Familiar feat (Dragon Compendium).
Cast any shapechanging spell and share it with your animal companion as long as it is within one mile of you.

[Jack_Simth]

Are there any? It would make such a great combination.

I appreciate those spells that change your animal companion or yourself into a single other creature, but not exactly what I'm looking for.

And by "shape changer" I mean, give it some sort of ability to wild shape, or polymorph itself, or use an ability like the Changeling. [Wands would probably work for this purpose, if you have an AC that can use them.]

With that wide of a definition? Yes. Anything that makes your animal companion intelligent will do, as it lets them take Use Magic Device. Arcane Hierophant's Companion Familiar, Exalted Companion from the Book of Exalted Deeds, and probably a few others (like, say, the Elemental Companion ACF). Possibly just a Headband of Intellect + 2, even. Once you get them to the point where they can activate magic items, you can actually make them fairly high end shapeshifters by way of a Skin of Proteous (http://www.d20srd.org/srd/psionic/items/universalItems.htm#skinofProteus), although that's a touch expensive.