We had a bad out break 8-10 years ago in replacement heifers and a few cows. 17 heifers treated, five could not see. They were pastured by a road to the stock yard with too much stock trailer traffic. We were lucky enough to get them into a trailer and carried them to a corral with shade. First day treatment was 6 ml bio-Mycin per 100 lb. sub-q , 5 ml . Bio-Mycin squirt in each eye with syringe , no needle. Next day , another squirt in the eye, next day same as the first . Fourth day, Vetericyn plus in the eye. Fifth day same as the first. sixth day vetericyn again. A lot of labor, after first day of spraying it was a real job to spray the eyes, good head gate and tied the head to limit head swing. Second week used Vetericyn every other day. All the animals recovered, the blind ones only had a small spot left and they were kept in the heard with no problems. Ever sense that out break we use 20/20 Vision with spur by Merck. We have not had any pinkeye using this vaccine on calves in March/April then early May. There are many strands, we are lucky this works in central Va. . Every year there farm here that have pinkeye some. The farm store learned to stock up on 20/20, some farms don't have a working corral, they probably work through a vet for limited success through feeds with medications in them.