You don't have to worry about about "feral" (I say that in quote because the description is relative. Canines probebly find themselves very advanced and refined, when compared to single-cell organisms) creatures learning how to talk, because they simply don't need to.
All animals possess a basic way of communication of one form or another. This can be body language, (Baring teeth - "I will put up a fight!", "Jazz paws" - "I want to play"/"I am friendly") Vocallisations, (growling - "I don't like this", Howling "I am here"/"Where are you?") ETC.
Given that almost all feral animals, with a few exceptions, can't bend non-living things to their will, AKA, use tools. This is more than enough for them! (The only unfortunate thing is, that some people don't (want to) speak "their language", wich results in misconceptions, and in some cases, abuse, that people get away with.)
We humans can use tools. And we have tools! Soo let's use a spanner as a basic example.
You can give a spanner to a person, but what if he doesn't know what to do it? Well, then you're going to have to explain this. And, if you want to explain that, you're going to have to "name" every item involved, (the spanner, a nut, an engine to work on, etc.) and the actions that the person needs to do in order to get the job done. Then you give him the instructions, by vocallising these "words" in the correct order, soo the person knows what to do. I.E, you say:
"Put (action, involves>) the spanner(designate item the action applies to) on(states that the former applies to> the nut, (designate item the action, using tool, needs to be done on) and turn counterclockwise.(Defines action that needs to be done using spanner, on nut)
The need to transferr complex commands, such as that, in a nutshell, is why humans have learned the advanced form of communication we call "talking".
In our human society, complex stuff needs to be done, like mechanics, calculations, economics, and complex communication is needed to get that stuff done. We humans simply can't suffice with the basic form of communications that "feral" animals have, because we need more.
Soo why don't "feral" animals speak?
Because they don't need to!
Let's say, a canine, can't pick up a wrench, or a spanner. He simply just physically can't hold it! Soo there's no need for a feral animal to learn how to speak, because what are they going to do with that information?
Before an animal learns how to speak, the species will first need to advance in both the intelligence to know what they could do with a "tool", and in the physiology, to be capable of physically using that tool.
Soo, in other words, pretty much all animals won't be capable of speaking, anytime soon...
Wanna see an animal that does?Yes, crows! Why?
Because crows have both the intelligence, and the physical capability to use tools.Soo, crows are probebly next in line, of learning how to speak!
Better prepare!