Here is my take on it.
Anything you can hit with a pistol in a defense situation is too big to be defending yourself from with a .22.
Can you hit a running housecat with a .22? IMO, anything bigger than a housecat or small to moderately sized dog will need more than a .22 lr to disable.
Simply put, are you expecting to be attacked by anything over 15 pounds? get a larger pistol. You WILL ALMOST CERTAINLY get hurt if you try to stop a dog with anything less.
Of course, granny smith's toy poodle may roll over and start to whine if you put a bullet in its tail, but many of the small terrier breeds will take that bulletin the spine even, and come back for more if they are really enraged.