Ahh I love dogs and all the things they get into.

Mine use to chew the tounge off my Combat boots. This usually happened right before I had to go to work.

As for the wireing issue.
I recommend that that redo the wiring yourself. Take your time and use heat shrink. It will be better then the factory stuff.

Go out and give your dog a atta boy. And then make sure that you take him for a long drive in the truck.

 

The best and cheapest places for trailer wireing is the camping trailer dealers. They do it all the time so they are good at it. Pretty reasonable prices to.