In the present study, we investigate the presence of metabotropic glutamate receptor 1 (mGluR1/GRM1) and glutaminase (GLS1/GLS) in canine oral malignant melanoma (OMM) and those of low malignant potential, termed histologically well-differentiated melanocytic neoplasm of the lips and oral mucosa (HWDMN). Here, GRM1 is linked to melanocytic neoplasm.