TH does run against some things JRRT had written earlier for The Sil, with
wolves being specifically associated with
Morgoth and
Sauron, though Draugluin and his ilk were said to be werewolves, while
Carcharoth, though Draugluin is said to be hi sire, appears to be more nearly a "normal" wolf, if of gigantic size and demonic ferocity.
In TTT, JRRT does not make as much of
Orc Warg-riders, I seem to recall that they seemed to function more like "cavalry" scouts rather than a compact attacking force. In the film, the attack on those heading for
Helm's Deep by Warg-riders (and
Aragorn's spill over the edge and all that baloney) are purely a product of PJ's fantasy. Then again, those
Wargs looked almost more like bears, or more properly hyenas, than proper wolves in LoTR the film. Their looks "improved" in TH - as did those of the
Eagles; in RoTK the Eagles seemed to me to be overblown hawks. But that whole Warg-rider bit was also blown all out of proportion in the TH films, and never mind that
Azog, main baddie of these films, has "really" been dead for 142 years, having been killed by the then young (for a
Dwarf)
Dáin Ironfoot at the climactic bottle of the
War of the Dwarves and Orcs, The Battle of Azanulbizar before the east-gate of
Moria in 2799 Third Age.
As I mentioned above, JRRT was still working the conventional fairy-tale formula here, which he was to reject quite firmly fairly soon after in his lecture "On Fairy-stories".
Besides the Wargs, the Eagles also speak,
Beorn's
animals can serve like waiters at the table …
... Referring to World War 2, no history book would refer to the Luftwaffe, the RAF or other air forces as an "army", no matter how much such forces influenced the outcome of war neither then nor now.
Well, actually, what is now the USAF was called the USAAF - the second A stands for "Army" - until the end of WW II. And the US Navy and Marines retain their airborne forces as an integral part to this day.
But more importantly, the Eagle would not be called an army because they were not from the start really allied with any side (though they definitely did not like
Orcs and hunted them at other times, too). The Orcs and Wargs were allies on one side, while the
Dwarves decided to forego an attack on the
Elves and
Men beleaguering
Erebor, and to join them as their far more natural allies, when faced with beyond-a-doubt enemies. The Eagles were in a way, as
Treebeard said about the
Ents, not really on anybody's side, as nobody was really on
their side. They were not to be counted on, but did have a habit of taking sides on short notice, as they also did before the
Black Gate, when they felt that one side was definitely
the one to support against the other.