How much Ivomec you give your pitbull would be determined by your dogs weight. Figure 1/10 of a CC per 10 pounds of dog weight. You should be aware that Ivomec is a strong medicine and should only be given with veterinarian supervision.
For adult pitbull, 1cc (about 50#)of Ivomec is a good dosage to put in the food. We don't usually put this on them unless we use Revolution or another topical.
Ivomec is actually a very strong medication and if you do not give the dog the correct dosage, there could be fatal consequences. I would recommend speaking to your vet to determine the correct dosage for your pitbull.