For something like this, I would actually think that copying the existing horse frames would be best. Each beast is done as a left half, right half, tail and head. There are enough parts on the frame to create multiple animals and some extra heads (jaw open, jaw closed, tongue lolling, etc.). I would do that as a base and then make a set of "tack" frames that could be added on or left off as desired.
Now you have "wild" or "tame" wolves!
Surely having multiple sprue molds for 1 basic model would increase
production costs several times over when 1 sprue would suffice.
The plastic isn't the real cost here. The real cost is in making the mold. It costs a LOT to mill out a stainless steel blank (although other options such as aluminum exist, they are less durable) and significantly less to get the plastic. If there isn't a great deal of duplication of parts, then it makes less sense to make mini-sprues.
Take the Shock Trooper frame as an example. There are three identical rifle arms, three identical left arms, two identical "other" rifles, three identical blast shield heads, three identical gas mask heads, and four(!?) identical mutant heads. By cutting the frame into "parts" it would be possible to increase the amount of goodies, but because you're only making one actual rifle "piece" you end up cutting down on the amount of milling possibly by 1/2!
For historic figures where you have many like poses (at least in traditional metals) if you assume that you could get three figures on a frame, you could cut the milling cost by up to 2/3 for rank and file figures.