As long as I'm here on BYC thought I'd throw in my experience regarding this...
A few years back I had a hen who had botulism (at first i thought it was a snake bite) ---she got all wobbly-- then she couldn't keep her head up --and could not stand...it got bad fast.
BYC form moderator advised (as best as I can recall ) giving her fluids through a dropper, I used watered down orange juice and watered down molasses...keep giving this very often I had the hen inside the tub with blankets at this point. I stayed up all night with her and three different times she became unconscious and I thought she died then she would move a bit. I had to keep holding her head and neck up for HOURS to keep the air passage open and fluids down. The next morning, as day broke, she lived through and I tried to stand her up --she could barely do it---it took several months b4 she could walk right. I still have this hen and she is such a sweet girl...i'm so glad I stuck with it.
My advice, if you love the chicken like I do, and you're willing,, and know it's botulism, (which by the way, they can catch from so many place not just maggots but lots of diff. bugs and even grains etc) keep her head/neck up and keep forcing the fluids down..I was told the molasses water helps break down (?) the poisons inside the animal...It worked for me!
(BE SURE to keep changing water for the other animals outside --but the hot temps (usually 90's usually cause this ) so they don't get it too. but to state the obvious --it's not catchy between them..
Good Luck... it's a terrible thing to have to watch your chicken go through and if you want to save them you have to be EXTRA attentive and basically sleep with the hen so you can get the fluids down..I forget if I had given any antibiotics so I won't say I did...again, Good Luck