NCAT (National Center for Appropriate Technology) has published a series of fact sheets slanted towards sheep production on irrigated pastures in the Intermountain West. Print copies are $3. Downloads (PDF files) are free.
The DrenchRite® test determines resistance to all anthelmintics and drug classes simultaneously from a pooled fecal sample. The test uses special assay plates that are made in Australia. Testing was recently halted because the plates were not available.