Those are all great suggestions.
Having only dipped into reading CW, I'm not familiar with the trollhound (beyond it's being monstrous). But one thing that springs to mind is (if it fits) having some kind of greater trollhound(s) show up at some point, and seriously impact the creatures' loyalties. Suppose the greater versions have some kind of innate sway with creatures of like kind. Maybe the companions would turn on their masters, so the PCs have to fight the greater trollhound(s), while suffering the bites and scratches of their companions (because they surely wouldn't attack the creatures they've nurtured and relied on!). And if the PCs kill the greaters, how do the companions react...?
And so as not to make this a gratuitous "I'm trying to take your animals/familiars away from you because they unbalance things" type moment, set it up so that the effect the greater 'hounds are having on the companions is very clear before there is any face off. Maybe some howling in the distance for a couple nights, that the trollhounds among the party react to in a distinctive way, a way in which handle animal and/or survival checks can interpret....
Just two cents off the top of my head.
(How did that get there?)
Gnome Boy (a.k.a. "Jon") • DCC play-tester @ DDC 35, Feb 2011. • Beta DL 2111, 7:00 AM PT, 8 June 11.Playing RPGs since 1977
• Quasi-occasional member of the Legion of 8th-Level Fighters.—Here Be DCC Monsters—VOORAK, L, Hunter, S10, A12, Sm10, P6, I13, L15, AC 10, HP 3, Spear +0 1d8, Init 0; R 0, F 0, W -1, Holy water, Pelt, 3 iron spikes, 1d ration, 4-leaf clover (Find secret doors) (+1), Com +1
SARKLA, C, Gatherer, S9, A14, Sm14, P15, I14, L8, AC 11, HP 5, Knife +0 1d4, Init 1, R 1, F 1, W 1, Chest, Basket of veggies, 2d ration, lg sack, waterskin, torch, Seventh son (Spell checks), Com +1
TARR, C, Hunter, S14, A11, Sm15, P13, I8, L8, AC 10, HP 3, Spear +1 1d8+1, Init 0, R 0, F 1, W 1, Holy water, Pelt, 4 torch, flint/steel, 1d ration, sm sack, Fox's cunning (traps), Com
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