I know this has been discussed, but, does anyone know the correct dosage for Baytril and when to start and for how long? TIA

You should be working with a vet on this. I keep antibiotics on hand for minor maladies but I always check with my vet to make sure that 1) it is the best antibiotic and 2) doseage is correct.

136 mg, once per day, for 10 days, beginning on day of first breeding.

Was the questioner asking about the breeding dosage of Baytril or for something else? I would clarify that before giving veterinary advice. JMHO.