How do tamed animals advance in hit dice?

[SorrySleeping]

I realize this is partly third party, but it deals with tamed animals/animals in general for core pathfinder rules.

The Beastmastery Sphere has a talent, Bolster Beast, that lets you add a hit dice to one of your tamed animal through a couple hours of work.

1) Is there any way to tell an animals HD other than its HP in its stat block?
2) What goes up for an animal when it gains a HD? Does it gain feats as normal, does it gain the +1 stat bonus at HD 4/8/etc.?
3) What are some of the better animal subtype creatures to use?

[blahpers]

1. Not that I'm aware of, but there may be some obscure feat, spell, or skill unlock somewhere.

2. It gains feats, BAB, attribute bonuses, saving throw bonuses, and so on.

3. Depends on what you mean by "better".

[LordKailas]

I'm not familiar with the 3rd party content you are referencing. I will say it depends.

If you're advancing an animal companion then you would reference the animal companion chart. If the animal in question is not an animal companion, it advances as per what's outlined under the animal subtype.

Animal Subtype wrote:

d8 Hit Die.

Base attack bonus equal to 3/4 total Hit Dice (medium progression).
Good Fortitude and Reflex saves.
Skill points equal to 2 + Int modifier (minimum 1) per Hit Die. The following are class skills for animals: Acrobatics, Climb, Fly, Perception, Stealth, and Swim.

and monster advancement rules

Monster Advancement Adding Racial HD: Step 3 wrote:

For every 4 additional Hit Dice gained by the monster, add 1 to one of its ability scores.

Monster Advancement Adding Racial HD: Step 4 wrote:

Creatures gain one feat at 1 Hit Die and one additional feat for every 2 Hit Dice above 1.

As far as I know, the only reliable place to look to determine a creature's HD is it's hp line.

SorrySleeping wrote:

3) What are some of the better animal subtype creatures to use?

better how?

[Artificial 20]

Obviously, all statistics derived from hit die would increase, which would include:
>Hit points
>Base attack bonus
>Saving throw bonuses
>Skill ranks (in practice, most animals gain 1 per hit die, due to having a steep int penalty, but you always get at least 1 before other features)
>More obscurely, some creatures' special features scale with hit die, like saving throw DCs that are calculated as 10 + 1/2 hit die + an ability mod

Aside from that, all creatures (unless specifically stated otherwise, e.g. mindless undead) use the same universal progression chart that PCs do. So that's a feat at 1st, 3rd, 5th etc. and a +1 to one ability score at 4th, 8th, 12th and so on using hit die in place of levels, pretty much as said.

Pretend you're levelling up a Commoner-class NPC and it's about the same.

[SorrySleeping]

I saw looking for that little stat block from the animal subtype, thank you LordKailas. The material let's you increase the hit dice of any animal you have tamed within a limit.

I'm asking about animals that don't have an animal companion version, or lose something as an animal companion. I know that the Axe Beak for example loses reach when in becomes an animal companion.

[Val'bryn2]

If it's not an animal companion, it's a basic animal, and you use the Bestiary statblock for it.