Doxycycline/micoplasma

[Mini chick]

I am looking for a some advice on dosing doxycycline 25g-200mg powder in the drinking water for treatment of micoplasma.
I have 4 sizzle bantams that suffer from reoccurring micoplasma. I normally treat with Tylan when this virus shows up but this time I decided to switch to doxycycline and see if it works better. Does anyone know how long to treat them for? I have had them on it for 12 days now

 

[dawg53]

http://www.poultrydvm.com/drugs/doxycycline
Just for your information, Mycoplasma Gallisepticum (MG) is a bacterial disease, not a virus. Doxycycline will treat MG.
Tylan is a very good product that treats MG. Since the Tylan appears to be ineffective, your bantams MIGHT HAVE a virus which would explain the ineffectiveness of the Tylan, and Doxycycline would be ineffective as well.
If it were a virus, I'd suspect Infectious Bronchites (IB) for which there is no treatment. It would have to run its course and birds usually recover over time with less egg production. You might see wrinkled egg shells and watery whites in the eggs if in fact your birds have IB.

 

[Eggcessive]

The doxycycline package directions for pigeons usually says to treat for 7-10 days. In order for any antibiotc to help a bacterial infection, enough of the water needs to be taken. I agree with @dawg53 that you might be seeing a virus. Infectious bronchitis virus lasts about a month and can spread throughout the flock over months. There are sometimes secondary diseases that can complicate any respiratory disease.