The assay is intended for use in evaluating {HEAD ~ the excreta} of {TAIL ~ an animal subject} 
of
The assay is intended for use in evaluating { HEAD ~ the excreta } of { TAIL ~ an animal subject }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL