Buying baytril/doxy online and dosing yourself?

I was wondering if it would be ok to buy these 2 meds online in case my rats have a URI flare up again. They're from a reputable source.
However, how would one dose them if you only have the weight of the rat? I'm not good at dosages.

Baytril is 10% and doxy is 20%

http://www.finchniche.com/product_baytril.php

http://www.finchniche.com/product_doxycycline.php

Some experienced rat owners do ..... but there are dangers as many drugs sold online have expired or are mislabelled and are not the correct drug.

I believe that it is much better to establish a good relationship with a good, experienced vet.
That way you know the meds are safe and the ones your rats need.

Also, you would be guessing as to what is wrong with your rat .... there may be fluid in the lungs, there may be other problems etc which is why going to a good rat vet is so important
Very experienced rat owners are able to treat many things themselves because of their learned knowledge but still relay heavily on their vets.

The amount of medication a rat receives is based on the weight of the rat (you need a digital scale - always a good thing to have), the concentration or strength of the meds, and the recommended dosage for rats for that medication.

I totally agree with SQ. I work in a veterinary hospital and we always caution our clients against buying medications online. Not only might they be expired or mislabelled as SQ said, but they can also be shipped without temperature control, counterfeit or come from an unauthorized source. Plus, if you do get your medications from your veterinarian, it makes it easier for your veterinarian to help your rat. ---There's not the added problem that the drug came from an unknown source and the manufacturer will help with any costs incurred if there are serious side effects.

There are many different medication options and your veterinarian may prescribe different drugs besides Baytril and Doxycycline.

I also agree with SQ that your vet may find there are other things going on that you wouldn't have noticed.