> the dosages are different, and the active ingredients differ
Neither the dosages nor the active ingredients are different. Both for humans and for animals, the recommended dose of Ivermectin to treat parasites is 200 micrograms per kilogram of body weight. The "active ingredients" are Ivermectin, period.
I have a bottle of injectable Ivermectin intended for cattle here, and it says it's pure Ivermectin in propylene glycol (typical carrier for injectables even for humans). I got it to treat Histomoniasis in our turkeys, which is btw an off-label use, because officially Ivermectin is not supposed to be effective against protozoa, but Histomoniasis is almost 100% fatal in turkeys and I haven't lost one since starting to give them Ivermectin as soon as I notice they have it. I've found that if I give them 600 micrograms/kg body weight every other day 3 times, they recover fully. What does this have to do with Covid? Only that a) Ivermectin works for some things other than those for which it's officially "blessed", b) at least in turkeys a much larger than normal dose doesn't seem to have any ill effects. As for the dose, I decided that it was probably safe for our turkeys because I read a paper where they gave that dosage to humans to combat malaria by making those humans lethally toxic to the mosquitos. The paper said the dose was "well tolerated". If they can do that to their human patients I can do it with my turkeys.
I'm not planning to inject myself with my veterinary Ivermectin even if I did come down with Covid... because I agree that so far the evidence that it's helpful isn't very strong. But I also think that this article is quite laughable... basically it says "Why You shouldn't use Ivermectin to treat or prevent Covid: because, uh... because we haven't said it's OK to do so." Sorry CDC, but your credibility just isn't /that/ high. And going to a hospital for /anything/ is also really dangerous... almost certainly more so than a couple of doses of Ivermectin.