Just curious, my pups 10 weeks,and old enough to be getting ticks on her... so I want to put frontline on her, but she's only 3 pounds,and the label says up to 22? that seems like an awful big does for such a small pup- yet,She needs it- we have other animals, and the bugs are WICKED this year! I'm thinking I should do it in 3rds, that should take care of the problem, b/c of her weight?