Nope, they are wrong, trust me. The 800 mg dose is 1.5 tablespoons, not 1 tablespoon. Just because a mfg says it should be something doesn't mean it's correct.
Look at their other errors. Since when does 1/2 tablespoon = 1 ounce?
100 gal containing 100 mg of tetracycline hydrochloride/gal
50 gal containing 200 mg of tetracycline hydrochloride/gal
25 gal containing 400 mg of tetracycline hydrochloride/gal
12.5 gal containing 800 mg of tetracycline hydrochloride/gal
The math is easy...
Each package has 10 grams (10,000 mg)
10,000 mg / 800 mg = 12.5 gallons medicated at 800 mg - This matches what http://www.drugs.com/vet/duramycin-10.html says.
Buy a package of it and see for yourself. Measure out the number of tablespoons. If there are 12.5 tablespoons, then the mfg is correct, but I think you will find that there are 18-20 tablespoons, which means the 800 mg dose is no less than 1.5 tablespoons.
Even better, weigh a tablespoon. How much you wanna bet that one tablespoon will weigh ~10 grams?
Package weight = 181 grams
181 / 10 = 18 tablespoons
Don't feel bad, I used to post the same misinformation.
One tablespoon of most powders used in poultry is gonna weigh 9-10 grams.
If you still don't believe me, find someone you know that's knows a little about math and ask them.