Use of macrocyclic lactones in cattle in the USA.

The use of macrocyclic lactones has become the main stay for the treatment of endo- and ectoparasites in the cattle industry. Here we review those drugs that are currently approved for use in cattle in the United States. The general efficacy, tissue distribution and toxicity of each drug formulation are discussed. Included is a discussion regarding the current status for nematode anthelmintic resistance in cattle populations within the United States. Also provided is a current summary of ecological effects of macrocyclic lactones residues in manure.