You seem to be really good at finding official type references. Are there any for blackhead medications that you have seen?Blackhead is caused by a protozoa. Treatment is 250mg metronidazole given orally once a day for 5 days. Then you have to eliminate the host that carries the protozoa...the cecal worm. Valbazen liquid cattle/sheep wormer will take care of the cecal worm....1/2cc given orally undiluted, repeat again in 10 days.