Suddenly, you remember!
Your faithful hound! Forty pounds is big enough to kill a man! Surely this animal's atavistic tendencies to rip and tear at any flesh presented to it will come awake at the slightest provocation if it loves you.
You throw the dog at the veterinarian. Kill him boy, you scream.
The vet's haughty expression changes as your dog's lips curl and a horrific squealing growl issues from his throat, but only for the briefest of moments before that squeal is muffled by the bare neck of the veterinarian as your faithful loving pet rips and tears and kills for you.
You knew it would work you knew your dog loved you.