Foley is more in depth than you think. Foley) is a sound added into movie or video game to add effects. the bark is "whatever you want it to be". Im not actually sure thats even the dogs name. Its just to throw you off. You hear the bark and dude says "whats that?" The other guy says "oh thats just foley" but theres no dog in the shot. Its a trick, They want you to think that and say "oh ok thats just the dogs name everytime I see or hear him bark" (franklin and dom missions).

When you kill sasquatch the human starts barking (woof woof). Frank asks "what's that supposed to be?" and sasquatch says "its whatever you want it to be" meaning you can make of it what you want, these things, the sasquatch or the dog, they were added in sounds and since noone really knows what a sasquatch sounds like, they made it woof as an example to us, the player, that its just foley.

If you hear a dog barking the dogs talking but the human has no idea what hes really saying so you make up what you want to hear. Its whatever you want it to be. Franklin just so happens to think the dog is telling him of dom in trouble. But is he really or is that just what frank thinks?

Chop barks near hidden objects, so does frank think chops saying "over hear theres an object"? We know he thinks that because game tells us that chop will bark when near things. Again its foley for us the player to know theres something nearby. If you want the bark to be a dog telling you something then think about what its telling you. You want it to be an alien than its an alien, you want it to be a sasquatch then its a sasquatch. But at the end of day it's just foley.