Ivermectin

Not sure what you mean. Do you mean how is it administered in general or how do we administer it personally?

How it is administered to a guinea pig. Or can you do any of them?

You can do it any of the three ways you listed in your first post. But you have to get the dose right, so read through these pages thoroughly before you treat your pigs, especially if you aren't taking them to a vet for treatment:
Guinea Lynx :: Ivermectin
Guinea Lynx :: Ivermectin Treatment Guidelines
Guinea Lynx :: Ivermectin Products
Guinea Lynx :: Ivermectin Topical Treatment
Guinea Lynx :: Ivermectin Oral Treatment

I've done topical and injections, and I wouldn't recommend administering ivermectin by injection unless you are very skilled at giving animal injections in the first place.

Ivermectin that was perscribed by our vet was either the liquid that you put in a syringe and they take it orally, or for the ones that were rescued and had bad scabs and major mites he gave them a injection at the office to. The topical that we recieved once I was told to give two drops on neck and lower back. I never really chose which type of Ivermectin. The vet would just give me one of the three and say here, do this and this. I personally think all 3 are good and have used them all. I just do not understand what you mean, I give it the method the vet describes and either use orally, topical or injection. Just depends on the Exotics Vet.

Okay, thank you. I just want to know so before I adopt my guinea pigs (or get them off craigslist-especially if off of craisglist) I can get some just in case. I want to get a few other medication things too, but I will always want to ask a vet before doing anything. I deffinitely won't want to do it by injection.
Oh what I meant was, I didn't know if you could only give ivermectin to a guinea pig a certain way like only orally or only injection, or only topical.

If you do need to order supplies online, I got everything here: (broken link removed) and they were great! If you need help with which syringes, needles, etc. to buy, shoot me an email or PM and I can help you figure it out.

Yeah, I will deffinitely buy from them! Thanks a bunch! I just might need help with the sryinges and such.

Read the links given you at guinealynx.

How you administer it depends on what form of ivermectin you get. The injectible you administer topically, the paste you administer orally, etc.