Well first off, I'd check the expiration date; Pfizer is no longer making that product so we don't know how old it is.
I found the manufacturing information on drugs.com (I need the number of grams per package - is it 10 grams per package?)
If so - 10 grams / 6.4 ounces = 10,000 mg/6.4 ounces
There are one 12.5 800mg dosages for one bag. (10,000mg/800mg = 12.5)
There are 20 500mg dosages for one bag (10,000/500 = 20)
6.4 ounces/20 = 0.32 ounces per serving at 500mg
0.32 ounces = 1.92 teaspoons. Since you can go up from the 500mg dosage, I'd do 2 level kitchen measuring spoon teaspoons per gallon of water.
That should be their sole source of drinking water daily - keep out of light if possible. Replace fresh daily. Do no less than 7 days, no more than 14. 10 is a good medium. Do NOT stop the medicines if you see the symptoms decrease - that means the meds are working and you should continue them.
If you see no cessation in symptoms after 48 hours, they say this:
"If improvement is not noted within 24-48 hours, consult a poultry diagnostic laboratory or poultry pathologist to determine diagnosis and advice on dosage." I'd go 48, not 24. That does not mean to stop medication - it means to check with maybe the local ag college to see if your dosage is too low.
Unfortunately these measurements are done in dry weight. But there's room both ways to keep the dosage in the right range to avoid problems with resistance. So you should be good.
Note: If you have a postal scale, it's a better source of measure. 0.32 ounces = 9.07 grams.
DO NOT USE yogurt with this - or milk products.
Because of the length of treatment, however, you MUST use some sort of probiotic. I recommend acidophilis capsules from the vitamin section of
walmart, the grocery store, pharmacies, etc. Or Probios dispersible powder from the feed store. Acidophilis = 1 capsule or tablet's contents per bird per day (empty the capsule, crush the tablet). Mix in a quickly eaten treat like cooked egg yolk (1 teaspoon), applesauce, or cooked oatmeal - whatever they'll eat quickly that is a little sticky. Do every day of medicating, and then ever other day for 2 weeks thereafter to replace the good bacteria in the gut that are unfortunately going to be killed in some part with the bad bacteria you're treating.