Hey Patches Mom,
I have a question and then a comment.
The question is why would you get a fire extinguisher to carrier in the scooter basket?
The comment is that fire extinguishers which discharge high pressure air and a powder (usually baking powder) or CO2 to put out fires--which is what most of the small ones are, can burn the heck out of a dog or you if discharged close to skin. They can blind a dog if discharged into the face. The air basically comes out supercooled and freezes what it touches if it is close. I know this from unfortunate personal experience and still have a healthy scar on my back from 25 years ago when someone was fooling around and got me with a little 2-1/2 lb extinguisher.
What has been pretty successful and less risky has been using one of the small handheld horns which take a compressed air can and make a whole lot of noise--it will usually deter.
I'd stay away from the fire extinguisher idea. Ammonia and water in a squirt bottle already recommended by someone else will also work well as will what you are using or lemon juice and water.
