Wow, that is a lot of ticks....If I may suggest in addition to the topical your using you could apply Cedrecide to her leg when she goes out. The smell repels ticks, I know it does kill fleas but it's supposed to have a effect on ticks too. I always have a quart on hand because it can be used on people too for mosquitoes. It's might be worth a try.....
TickShield - Industrial Strength Organic Insect Spray - CedarCide : CedarCide