take some wire strippers and some black tape to join the wires your dog has chewed apart, they are color coded inside the outer plastic coating. if there is a section that the dog has just chewed but not the whole way through you can just cut that section out.

when you join the wires back together make sure the little strands from each seperate wire do not touch each other.
join one wire together at a time and then insulate each strand well before moving onto joining the next wires. i have repaired many chewed upon wires and it is simple and can be fun once you have fixed up your speakers yourself without buying new ones.