I have a bitch that I want to clean out before I breed her. She has had mastitis in the past and was looking through the bible and it said to us (cephalexin). My question is she is 45 lbs, how much should I give her? I also could only find 250 mg of Fish Flex at my local feed store, do I just double up on it? Just want to make sure I got the dosage straight before I start treatment.