Hi Pam, a baseball bat properly applied to the skull of any dog will achieve the desired result. Frequent applications may be necessary but a baseball bat is easy to reload. Stun gun - does not inflict pain. It short circuits the electrical impluses in the body and cause the muscles to do weird things. It will normally stop an animal especially a short haired dog. The contact where the 50,000 volts will arc should make contact with the conductive material - skin. The reaults will be quite rewarding and depending on your mood entertaining. Don't do it for fun. I was hit with stunguns in training and even though I expected and prepared for the shock is was must debilitating. Pepper spray - you can carry pepper spray or mace since liberals frown on us walking around with loaded shotguns. There is no way to actually prevent any of the situations from occurring unless you lock yourself in your home and never take your dogs out. There will always be some inconsiderate person who wants their Fluffy to play with your manstopper or their manstopper to have a romp with your Fluffy. Either way - something unpleasant may happen. Small furry dogs are just like small furry critters to a terrier type dog. They scurry along the ground just like those tasty squirrles, rats and other delectable treats. If you have the small furry critter on your leash and have attracted the unwanted attention of small furry critter hunter things will get exciting. In scenario 1 - pickup your little dog and walk away. If you are chased and you fear that you will be attacked you could try confronting the attacking dog and basically turning the tables on it. Yell at it and make yourself look bigger and more dominant and aggressive. .. Not sure if this will work in all cases but if the dog is not too serious it may just decide that you are a hassle and your furry critter is not worth the effort. More knowledgable members will disagree - or have other solutions. Scenario 2 - You have a bigger dog (large breed) let it protect you. Even those breeds you mentioned are still dogs and will confront another dog if pushed. Hardware is more reliable than software in this case also (I think Frank said that). If something has to get bitten let it be the dog. (here comes the storm). Secnario 2 has happend to me twice. Staring a non threatening dog in the eye could provoke a confrontation. If the dog is already aggressing then starring it down could defuse or escalate the situation. It depends on the dog and the situation. Good question - standing by for more input.