Dosing dogs with horse dewormer?

I own 9 great danes and a mutt (not a collie mix) and I am wondering if someone can tell me the break down of safeguard/panacur 10% paste in the tube for horses for my dogs. Before anyone respondas negatively about buying dewormer from the vet please know that it costs a FORTUNE and this is the SAME EXACT stuff...it just has not been broken down in a liquid form yet...it is a paste. I have been using ivermectin 1% swine/cattle dewormer for years on my dogs for heartguard prevention via my vet but he is on vaccation so I would have just asked him this if I could have. I have been told that you can do 1 part paste to 2 parts distilled h20 to make it into the liquid form if needed....but I do not know the dosage for this. Any help will be appreciated and any negative responses will be ignored. My danes are 100-180# depending on the dog. I have all of there accruate weights from there vet visits when they all got there boosters and yearly rabies. Thanks!