- Efficacy of a pour-on formulation of eprinomectin (MK-397) against nematode parasites of cattle, with emphasis on inhibited early fourth-stage larvae of Ostertagia spp. Williams, J.C., Stuedemann, J.A., Bairden, K., Kerboeuf, D., Ciordia, H., Hubert, J., Broussard, S.D., Plue, R.E., Alva-Valdes, R., Baggott, D.G., Pinkall, N., Eagleson, J.S. Am. J. Vet. Res. (1997)