I'm pretty sure Baytril is prescription only. Plus, your vet is the only one who will be able to give you the proper dosage. At least in our city our small animal vet is VERY reasonably priced when we have to take out ferrets in. I'm sure your vet will help if they do get sick so it's not worth the risks of trying to diagnose and treat a problem yourself with medication that might not even be the right one.
No, Baytril is only available through a licensed veterinary facility. Besides, "sick" can mean a lot of things, and many of them can't be treated with Baytril.
Hey, I'd pm you if I could but I'm a new member and don't even have five posts yet . Feel free to pm me your email addy or something though and I can give you some info.
I do agree that you need to have an experienced small animal vet to prescribe meds for your rat.