Dear db, I have little experience except as follows. Using dosage in Highfields book, I carefully weighed the apple flavored Panacur paste after weighing the tortoise and put the paste on a grape leaf or lettuce leaf, rolled it up and hand fed it to my Russians and Leopards. I was fortunate the tortoises were all vigorous feeders. Some "squished out the mouth", so the dosages were not real precise, but the administration was not stressful unlike others. Panacur seems to offer a wide range of dosage and still be effective and safe in my limited experience. I was amazed at the obvious effect on the tortoises, which expelled a lot of round worms. I repeated the dosage 10 days later. You may need to tube administer with a catheter, and you will need a vet or experienced person to show you. My tortoises were outwardly healthy and feeding well, but obviously had a belly full of worms which were expelled. Good luck, Vic H.
P.s. Worm eggs may infest the soil, so try to interrupt the cycle while you clean the tortoises out. Ask your vet about it, it depends on what type worms your animals are dealing with.