Endoscopy and biopsy of the caudal gastrointestinal tract were performed pretreatment and on the last day of a 21-day treatment period with ( 1 ) oral carprofen ; ( 2 ) carprofen and the proton-pump inhibitor lansoprazole ; ( 3 ) carprofen , liquorice extract , and a herbal solution that contained extracts of thyme , icelandic lichen , hyssop , and saponariae root ; ( 4 ) robenacoxib ; ( 5 ) robenacoxib and lansoprazole ; ( 6 ) robenacoxib , liquorice extract , and herbal solution ; or ( 7 ) an empty gelatin capsule .