A spray bottle and mace will pretty much give you a light mist that can come back at you.
I would recomend a Kimber pepper blaster.
http://www.pepperblaster.com/
It is made by kimber fire arms and delivers a dense pepper laden foam at 90 mph... and you have a second shot if you need it.
You can carry it in a pouch on your belt line that looks like a PDA or cell phone.
This would be a much better choice for dogs or a mugger.
I also carry a benchmade spring assist knife just to be on the safe side. I always have to cut open boxes, and had to cut someones seat belt after an accident once so I always try to have a knife on me. I choose spring assist too add some speed if I am attacked.
I know this is a bit of an odd first post but I strongly belive in taking safety seriously.