While this has been discussed in several other places in the past, no one has yet pointed out to you in this thread that there is a clause in the Penal Code that does cover defense against attacking dogs. Chapter 9 gives you the defense of necessity. It does not mention dogs directly, but says that you can do almost anything to protect yourself if the harm caused by your doing it is less than the harm caused by allowing the other activity to continue. The key point is that your actions must be reasonable.
Other than members of PETA and some (not all) members of HSUS, the average person is going to agree that protecting a child in a stroller from an attacking dog is a reasonable action. I think I would have shot the dog as it approached the stroller.
Obviously, you must have done something right in this case since everyone went home unharmed. I understand why you would want to know in case of future attacks though. So, my first answer is to always protect yourself and your family from any attacking animal. A gun works well if you are willing to use it (dogs don't seem to understand the threat implied in pointing it at them
). Pepper spray was actually first invented (as I understand it, may be wrong) by the post office as a dog repellent for its carriers. This may be apocryphal but it works better on dogs than on some people. Tasers are NOT recommended for use on animals as they seem to want to attack worse as soon as the charge stops.