In our area 4G (concentration of 4000mg per pound) or 2G crumbles contains chlortetracycline. Should be able to find something similar in your area.
Contact a Vet about the dosage. Mix with feed around 3 of feed to 1 of antibiotic of the 2G (2000mg per pound concentration).
I have fed 2000mg per head on 1000 pound cows until eyes quit weeping. Usually about a week.
I am not a Vet. Remember....Contact a Vet about the dosage.