I am enjoying playing you. You have a great story and are very scary.
However, there was no reason to kill that dog, Max the lab. I am very disappointed in you. It was not necessary for the story and made me very sad.
A great horror story (movie, book or game) can, if done properly, kill any character and not lose the audience - but you never kill the dog. It simply isn't done.
When in doubt ask yourself "would Dean Koontz kill this dog in his story?'. The answer will always be no. So no. Don't do it.
P.s. Dying of old age is acceptable though frowned upon.