In a few weeks I'll be starting a converted Skaven army, and part of their lore has to do with Warpstone mutating some dogs into dog-men. I'm wondering if Warpstone has the power to change a non-sentient warbeast into a sentient, bipedal being, or if the mutations are more random, giving the victims things like extra bulk, tentacles, or a second head.
It's raw Chaos condensed. Whatever happens via Chaos, can probably happen via warpstone. For example, Beastmen... ....and Chaos Spawn.... ...are probably likely. If in doubt do what you want
Heard-smelt Warpstone! Where-where?! Oh, it's you lot. Warpstone can cause all manner of mutations and horrific side effects. For those like Clan Moulder who can (sort of ish) control such mutations, they can create anything. To quote Mordheim: The value of the wyrdstone shards is not simply the coin that nobles and merchants are willing to pay for them. It is a well-known fact that the stones are rich in magic, and they are said to grant a variety of powers to those that learn to use them. Tales are told among the common folk of stones that caused a certain farmer’s harvest to double, or of the stone that made old Herr Grutenbauer's dog speak like a man. True or not, these tales hint at the powerful and chaotic forces at work in the stones. The most common use for the stones’ magic has to do with the discovery of the famed alchemist van Hoffman of Reikland. It was he who first observed that Wyrdstone can serve as a catalyst in the transmutation of base metals into gold. This usage of the stones has come to be the primary obsession of those who seek it, for many are willing to pay princely sums for stones that will make them an even larger fortune. Yet there are those who continue to seek the stones for their more arcane uses, and even mercenaries have been known to keep a stone or two that was thought to bring luck, healing, or other magical benefits. Yet the stones are ultimately the work of Chaos, and those who seek to use them often learn to fear their magic rather than harness it. For every tale of a harvest that doubled, there are two about the harvests that rotted in the field when exposed to the strange glow of the stones; and for every tale of a dog that learned to speak like a man there are darker tales of animals that turned into a gruesome parody of a man-beast. The tales of magical healings are mixed with many of mutation and death brought on by exposure to the stones. Yet greed is the downfall of many in the City of the Damned, and the greed for power is perhaps the greatest of all... It is possible for a stable(ish) mutation like Skavenkind or Beastmen with another humanified creature like dogs, cats, pigs, e.t.c. Although chances are a whole Clan of such creatures were created by intent from some dark god, daemon, or mastermind (maybe a renegade Skaven from Moulder who retreated to an island where he created a race of human-like animals? Island of Dr Moreakk?)
Yet would Skaven accept those creatures into their Clans? I would imagine you would know that because you have some information on Skaven, the kind that only a Skaven would know.
The answer is: Skaven will do anything that gets them ahead. If they're reasonably sure that this horde of dogmen won't betray them until they're ready to be betrayed, they'll work with them. Bonus points if they can then betray the dogmen.
To be fair, Skaven wouldn't accept other Skaven into their Clan. The only worthy Skaven to be in their Clan is themselves, and they are each the one true Skaven to lead Skavenkind into Ascension. Forgetting Skaven nature towards themselves, Skaven view all other races as inferior. A non-Skaven race would be reduced to slaves or food. However, if the Skaven could be convinced that these new fangled Dog Warriors make good bodyguards and loyal cannon fodder then all the better. In fact, if they truly believe this race could be even a temporary boon for their own goals, they'd form some kind of temporary alliance.
And if some backstabbing happens, could a clan be led by the dog-men? (Dog-person kills original clan warlord, demotes various other leaders, puts other dog-men into now-empty positions of power...)
The strongest and most cunning Skaven are usually the ones in charge. If a dog-person took down a Skaven warlord and took his place, the other Skaven would accept him/her as the leader until they can muster their own strength or cunning plan to overthrow him. Skaven are cowardly, sychophantic, and conniving creatures, so if something clearly powerful and smart did come in and say "I'm your new boss now" they'd reply with a "yes-yes sir" but slowly try and find a means to kill this new leader.