A 6-year-old, intact male Schnauzer was referred 2-days after accidental ingestion of baked garlic. Regenerative anemia (Hematocrit 22%) and the elevated methemoglobin (8.7%) concentration were detected upon hematological examination. Eccentrocytes, Heinz bodies and ruptured red blood cells were also noted on blood smear films, which were the results from the oxidative injury of the Allium species. The dog was hypertension (systolic mean 182 mmHg) concurrent with other clinical signs, such as vomiting and dark brown urination. Treatment with continuous oxygen, antioxidant drugs and antihypertensive therapy resulted in good progress. The dog was discharged 4 days after hospitalization. There were no remarkable findings in the follow up hematologic examination 24 days after discharge, but the dog still had a high blood pressure and continued on antihypertensive therapy. No recurrence was noted and the blood pressure returned to normal levels 4 months later.