After hitting the first porcupine, dogs either learn to fear them, or seek revenge and try to kill everyone they find. Dogs need to be broke and learn to hold a point weather it's on a bird, snake or porcupine. Shock collars can be used to break a dog, but it's not the best way for a soft temperament dog.
Tritronics make the best collars. Long battery life, expandable with extra collars, waterproof, durable and easy to use with multiple dogs. They do tend to be the more expensive option, but I've had models that still work after 10 years.