Some are sub Q. Some are IV only. Some are I'm. I hope you aren't considering injecting your dog with anything and asking that question? Make a mistake and you can cripple or kill your dog or all kinds of nasty things so it's really best left up to your vet as the results can be far more expensive than having the vet do it in the first place if that's the issue. Skin grafts, life saving emergency, amputation, and painful death all can be some results of your mistake (oh, and maybe if someone gets upset the fines) and how do you know you are using the right antibiotic and won't make things worse? Do not try to treat your dog if you don't know exactly what your doing and have to ask questions like that. Your vet went to school for years to learn that and still looks things up in books and things you might not have and also has experiences not in the books and is still learning every day. Even vets try to be sure they know what they are treating before they do so.