Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly used in animals, especially in dogs, to manage pain due to inflammatory disease. This study investigated whether plant drugs can prevent mucosal injury induced by robenacoxib. We used fifteen healthy beagle dogs (7 male and 8 female) aged 4 months, weighing 4.2-5.1 kg at the beginning of the study. Endoscopy and biopsy of the colon were performed before and on the 21 day treatment with robenacoxib (1), robenacoxib, herbal solution with liquorice extract (2), placebo -an empty capsule (3). There were 5 animals in each group. The greatest microscopic damage in the colon was observed in animals which received robenacoxib. Plant drug administration reduced the severity of lesions in the colon when administered with robenacoxib (ARI = -0.15). Conclusion: concurrent administration of liquorice extract and plant solution with robenacoxib was associated with significant decreased severity of the robenacoxib-induced colonic mucosal lesions.