Sorry, I didn't see the question here. We use the sheep drench version Ivermectin so no injection required (and not all breeds can handle Ivermectin, so be very careful with this). We actually had help from our vet in determining dosage - she's a farm vet and handles both dogs and sheep, which I'm sure helps. The sheep drench is more dilute than the cattle dosages. But research carefully, or better, both do the research and find a country vet to check behind you before administering.