They're weight is too low for this product, I suggest looking at http://goo.gl/qGj7ku for less than 22lbs

The active ingredient in Valueheart is ivermectin.

Hi You do not need a prescrition to buy Valueheart from us. With regard to the size these are guide wieghts given for small breeds, medium breeds and large breeds. As your dogs are at the crossover point it is best to check with your vet.