A 16-year-old, spayed female, Maltese dog weighing 4.3 kg was presented with a 2-week history of yellowish nose-and oral-discharge, anorexia and lethargy. In physical examination, indefinite ulcerative mass about $3{ imes}3$ cm in size in the left sublingual region, severe gingivoperiodontitis, halitosis, moderate dental calculus, fever and swelling of mandible soft tissue were noted. In radiographic view, periodontitis and bone lysis findings on the left rostral part of maxilla and mandible were observed. In complete blood count and blood chemistry test, thrombocytosis, increased levels of serum $NH_3$, AST and ALP were obtained. Urinalysis revealed hematuria and proteinuria. In histological examination, squamous cell carcinoma was diagnosed. No surgery was performed, but combined treatment with carboplatin and piroxicam was initiated. Five days after initiation of medication, because of insistent vomiting, piroxicam was substituted to meloxicam. Although the therapeutic efficacy of meloxicam could not be known; administration of meloxicam might be less potential to gastrointestinal side-effects than piroxicam. The dog totally received 3 times of carboplatin infusion. Five days after third infusion of carboplatin, the dog was hospitalized with severe lethargy, vomiting and bloody diarrhea. In examination, severe renal failure signs were noted, and the dog was euthanized.