Quick question: Polymorph and comanions

[Talakeal]

What happens if someone casts a permanent polymorph spell on a familiar / animal companion / paladin mount / etc and changes its type?

Also, is there any way for said animal companions of various types to advance by class levels instead of HD?

[Righteous Doggy]

Are you asking us to give you a way to create a broken pet?

[Talakeal]

No, it was just something that came up in a game I played in several years ago and none of us could figure out how to resolve it.

[Dr.Orpheus]

Generally nothing you do can cause a familiar, animal companion, or spawn to grow in level. Cohorts and followers can, but they have a limit on how high a level they can be relative to your level. If you want a cool pet polymorph it into an Umbral Blot.

[eggs]

What happens if someone casts a permanent polymorph spell on a familiar / animal companion / paladin mount / etc and changes its type?They're all clear in the ways they improve the familiar - a few HD in animal or Magical Beast or similar. Even a permanent PAO is still just a PAO.

Also, is there any way for said animal companions of various types to advance by class levels instead of HD?
Leadership can make the Special Mount a cohort. The other companion types would take some houseruling.

[Talakeal]

So, if I were to cast PAO on my familiar and turn it into say, a dragon, the spell works and I still retain a dragon as my familiar even though it is no longer a tiny animal or on the list of available familiars?

[Pilo]

Yes, because it doesn't really change your familiar/compagnon.
The effect can end or be dispelled (it does not change his level or is LA).

[NM020110]

If your familiar were hit by a baleful polymorph, and the result ended up no longer being on the list of familiars, would you then lose that familiar?

Sorry if that seems a bit roundabout for an answer, but I feel that the best and worst case should be considered when making a rules decision.

Personally, I would rule that using polymorph any object on the familiar would change its form, and that the familiar bond would be retained. However, if a second casting were to make the shift permanent then the original form would be lost, and the creature would exceed the bounds of the binding magic used to create the familiar bond.