The male could still be infected with coccidiosis but not as much as before when he was showing signs in the droppings. Likewise, he could still have a URI or other type of infection that hasn't been eradicated. Also, I think I remember you saying that you had already treated the birds for airsac mites. It's also possible that, with this male not singing, he might have airsac mites that wasn't eradicated with the prior treatment.
What is the recommended dosage on the tetracycline you have?
The problem with ingredients being listed in I.U.'s is that different substances that may have the same I.U. can have different weights. So, it can be difficult to convert I.U.'s to milligrams or teaspoons. For example, the tetracycline that we use and sell -- Tetratex -- is FDA guaranteed human grade tetracycline hydrochloride, and each level teaspoon of Tetratex contains 250 mg of tetracycline.
The product you have is a combination of tetracycline and erythromycin. And, with the I.U. information, I don't have any way of determining how many milligrams of tetracycline are in, say, a teaspoon to know whether the dosage rate is strong enough or not.
Michele
