The power company is responsible for faulty lines within its control and thus responsible for the damages those faulty lines cause.  However, was the line modified by someone else?  Who put the splices in the line?  If they are completely responsible for the faulty line, then they owe you full damages for the dog.  I have made a claim against Entergy before and was only successful by taking them to court.  You may have to take them to court to get the full amount.